feat: instant local search results while full pipeline runs

Added SearchLocal() — queries only the FTS5 index with no network
calls. The frontend now calls SearchLocal first, renders those
results immediately (clearing the loading spinner), then fires the
full Search() pipeline in the background. When full results arrive,
they replace the local hits seamlessly.

For indexed queries this means sub-100ms first results regardless
of how slow MB/LB are. Unindexed queries still show the loading
spinner until the full pipeline completes.

frontend/src/components/explore-view/explore-view.ts

@@ -1,7 +1,7 @@
 import { LitElement, html, css, nothing } from 'lit';
 import { customElement, state, query as litQuery } from 'lit/decorators.js';
 import { designTokens } from '../../styles/tokens.css';
-import { Search, GetThumbnails, GetArtistImageURL, CheckLibraryMBIDs } from '@go/explore/Service';
+import { Search, SearchLocal, GetThumbnails, GetArtistImageURL, CheckLibraryMBIDs } from '@go/explore/Service';
 import type { ThumbnailRequest } from '@go/explore/Service';
 import type {
     MBSearchResult,
@@ -520,6 +520,29 @@ export class ExploreView extends LitElement {
         const startTime = performance.now();
         console.log(`[explore] search started: "${query}"`);
 
+        // Phase 1: show local index hits instantly (no network).
+        try {
+            const local = await SearchLocal(query);
+            if (version !== this.searchVersion) return;
+            if (local && (local.artists?.length || local.releaseGroups?.length || local.recordings?.length)) {
+                this.results = local;
+                this.loading = false;
+                this.loadThumbnails();
+                this.loadArtistImages();
+                this.checkLibrary();
+                const elapsed = (performance.now() - startTime).toFixed(0);
+                console.log(
+                    `[explore] local results: "${query}" in ${elapsed}ms — ` +
+                        `artists=${local.artists?.length ?? 0}, ` +
+                        `albums=${local.releaseGroups?.length ?? 0}, ` +
+                        `tracks=${local.recordings?.length ?? 0}`,
+                );
+            }
+        } catch {
+            // Local search failed — continue to full search.
+        }
+
+        // Phase 2: full pipeline (MB + LB + reranking).
         try {
             const result = await Search(query);