feat(wails): move the frontend onto v3's generated bindings

frontend/wailsjs/ is deleted and frontend/bindings/ takes its place —
a real TypeScript module tree nested by Go import path, generated by
wails3's static analyser rather than by building the app and running
it.  The @go alias absorbs the constant prefix, so a call site imports
'@go/library/library.js' and the codemod over all 93 sites was a
specifier rewrite plus splitting @go/models' namespaces into one
import per package.

The 12 SetContext bindings and the fake `context` model are gone, as
Phase 2's ServiceStartup port promised: 272 methods across 12
services, none of them plumbing.

@runtime/runtime is now a local shim (src/wails/runtime.ts) over
@wailsio/runtime, so the 22 EventsOn imports are untouched.  It
unwraps v3's WailsEvent into v2's callback shape, which is exact here:
nothing in backend/events passes more than one data argument, and v3
only packs arguments into a slice when there is more than one.

v3 tells the truth about two things v2 lied about, and that is most of
the diff.  A Go nil slice really does arrive as JSON null, and a Go
named string type really is an enum; v2 typed them as T[] and string.
utils/binding.ts states the app's actual contract — an absent list is
an empty list — once, at the boundary where it is true, and also drops
the CancellablePromise the app never cancels.  Four test fixtures
widen an enum field back to its value union.

Not done, and Phase 5's to fix: frontend/test/support/wails-fake.ts
still fakes window.go, which v3 does not have, so `make ui-test` is
broken and harness.test.ts fails to compile on EventsEmit.  That test
also asserts v2 ordering that no longer holds — v3's Events.Emit calls
the backend and does not notify in-page listeners at all.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UDCbcCZQepnpSQYJ6SxxZm

frontend/src/components/config-page/config-page.ts

@@ -2,14 +2,14 @@ import { LitElement, html, css, nothing } from 'lit';
 import { customElement, state } from 'lit/decorators.js';
 import { repeat } from 'lit/directives/repeat.js';
 import { EventsOn } from '@runtime/runtime';
-import type { explore } from '@go/models';
+import type * as explore from '@go/explore/models.js';
 import {
     AddLibrary,
     RenameLibrary,
     RemoveLibrary,
     GetRemovalImpact,
     GetAllLibrariesWithTrackCounts,
-} from '@go/library/Library';
+} from '@go/library/library.js';
 import {
     GetScanConcurrency,
     SetScanConcurrency,
@@ -17,17 +17,17 @@ import {
     SetDefaultPage,
     GetQueueFallback,
     SetQueueFallback,
-} from '@go/config/Config';
-import { GetIndexStatus } from '@go/explore/Service';
-import { DirectoryPicker } from '@go/frontendutil/FrontendUtil';
+} from '@go/config/config.js';
+import { GetIndexStatus } from '@go/explore/service.js';
+import { DirectoryPicker } from '@go/frontendutil/frontendutil.js';
 import { notificationStore } from '@store/notification-store';
 import { describeError, explainError } from '@utils/describe-error';
-import type { library } from '@go/models';
+import type * as library from '@go/library/models.js';
 import { ThemeController } from '@store/controllers/theme-controller';
 import { TrackListController } from '@store/controllers/tracklist-controller';
 import { FavoritesController } from '@store/controllers/favorites-controller';
-import { GetAllPlaylists } from '@go/playlist/Service';
-import type { playlist } from '@go/models';
+import { GetAllPlaylists } from '@go/playlist/service.js';
+import type * as playlist from '@go/playlist/models.js';
 import { Events } from '../../events';
 import {
     SHORTCUT_CATEGORIES,
@@ -49,6 +49,7 @@ import './shortcut-capture';
 import { confirmAction } from '../confirm-dialog/confirm-dialog';
 import { shortcutsStore } from '../../store/shortcuts-store';
 import { ShortcutsController } from '../../store/controllers/shortcuts-controller';
+import { list } from '@utils/binding';
 
 const SCROLL_STORAGE_KEY = 'yj-now-playing-scroll-mode';
 const SCROLL_CHANGE_EVENT = 'yj-scroll-mode-changed';
@@ -1012,9 +1013,9 @@ export class ConfigPage extends ViewLifecycleMixin(LitElement) {
         const ok = await confirmAction({
             title: 'Remove library',
             message: `Remove “${libName}”?`,
-            impact: `This deletes ${impact.trackCount} tracks, affects `
-                + `${impact.playlistsAffected} playlists and removes `
-                + `${impact.queueItemCount} queue items.`,
+            impact: `This deletes ${impact?.trackCount ?? 0} tracks, affects `
+                + `${impact?.playlistsAffected ?? 0} playlists and removes `
+                + `${impact?.queueItemCount ?? 0} queue items.`,
             confirmLabel: 'Remove',
             danger: true,
         });
@@ -1187,8 +1188,7 @@ export class ConfigPage extends ViewLifecycleMixin(LitElement) {
 
     private async loadPlaylists(): Promise<void> {
         try {
-            this.playlists =
-                await GetAllPlaylists();
+            this.playlists = await list(GetAllPlaylists());
         } catch (err) {
             console.error(
                 'Failed to load playlists:',
@@ -1456,10 +1456,10 @@ export class ConfigPage extends ViewLifecycleMixin(LitElement) {
                                            <span class="index-stat">updated ${this.timeAgo(s.lastBuilt)}</span>`
                                     : nothing}
                             </div>
-                            ${s.tiers?.length > 0 && s.tiers.some((t) => t.state === 'running' || t.state === 'pending' || t.state === 'error')
+                            ${(s.tiers?.length ?? 0) > 0 && (s.tiers ?? []).some((t) => t.state === 'running' || t.state === 'pending' || t.state === 'error')
                                 ? html`
                                     <div class="index-tiers">
-                                        ${s.tiers.map(
+                                        ${(s.tiers ?? []).map(
                                             (t) => html`
                                                 <div class="index-tier">
                                                     <span class="tier-icon">${this.tierIcon(t.state)}</span>

frontend/src/components/config-page/download-clients.ts

@@ -14,10 +14,12 @@ import type {
     ProviderField,
 } from '@store/download-store';
 import { downloadStore } from '@store/download-store';
-import { DirectoryPicker } from '@go/frontendutil/FrontendUtil';
-import { GetDownloadPreferences, SetDownloadPreferences } from '@go/config/Config';
-import { SetPreferences } from '@go/download/Service';
-import type { download } from '@go/models';
+import { DirectoryPicker } from '@go/frontendutil/frontendutil.js';
+import { GetDownloadPreferences, SetDownloadPreferences } from '@go/config/config.js';
+import { SetPreferences } from '@go/download/service.js';
+import type * as download from '@go/download/models.js';
+import { Format } from '@go/download/models.js';
+import { compact } from '@utils/binding';
 import { describeError, explainError } from '@utils/describe-error';
 import { confirmAction } from '@components/confirm-dialog/confirm-dialog';
 import './config-section';
@@ -28,15 +30,15 @@ import './config-section';
  * deliberately excluded — it names "no format detected", not a format a
  * user could opt into.
  */
-const AUTO_DOWNLOAD_FORMATS: { value: string; label: string }[] = [
-    { value: 'flac', label: 'FLAC' },
-    { value: 'alac', label: 'ALAC' },
-    { value: 'wav', label: 'WAV' },
-    { value: 'mp3', label: 'MP3' },
-    { value: 'aac', label: 'AAC' },
-    { value: 'ogg', label: 'OGG' },
-    { value: 'opus', label: 'Opus' },
-    { value: 'wma', label: 'WMA' },
+const AUTO_DOWNLOAD_FORMATS: { value: Format; label: string }[] = [
+    { value: Format.FormatFLAC, label: 'FLAC' },
+    { value: Format.FormatALAC, label: 'ALAC' },
+    { value: Format.FormatWAV, label: 'WAV' },
+    { value: Format.FormatMP3, label: 'MP3' },
+    { value: Format.FormatAAC, label: 'AAC' },
+    { value: Format.FormatOGG, label: 'OGG' },
+    { value: Format.FormatOpus, label: 'Opus' },
+    { value: Format.FormatWMA, label: 'WMA' },
 ];
 
 /**
@@ -607,7 +609,7 @@ export class DownloadClients extends LitElement {
         // Secrets are never sent back to the frontend, so their fields
         // start blank; a blank secret on save means "leave it alone"
         // rather than "clear it".
-        this.draft = { ...(provider.settings ?? {}) };
+        this.draft = compact(provider.settings);
     }
 
     private cancelEdit = () => {
@@ -748,7 +750,7 @@ export class DownloadClients extends LitElement {
         }
     }
 
-    private toggleFormat(format: string, checked: boolean): void {
+    private toggleFormat(format: Format, checked: boolean): void {
         const current = this.prefs.allowedFormats ?? [];
         const allowedFormats = checked
             ? [...current, format]