fix: smart playlist UX polish — layout, defaults, free-form input, case-insensitive matching

Details view:
- Skip evaluation on new playlists (was returning all 25k tracks)
- Go straight to editor on auto-edit instead of awaiting loadTracks

Editor:
- Default sort to Random instead of None, remove None option
- Hide sort direction button when sort is Random
- Fixed-width field (160px) and operator (140px) columns, value fills remaining space
- Preview fills remaining vertical space (flex layout) instead of fixed 200px max-height
- Preview scrolls independently while rules/options stay pinned

Combobox:
- Accept free-form text on blur and Enter — no longer requires selection from dropdown
- Enables typing values like 'indie' that may not be exact DB entries

Backend:
- Case-insensitive text matching: COLLATE NOCASE on is/is_not/is_any_of operators
- Applies to both regular fields and genre subqueries
- LIKE operators were already case-insensitive (SQLite default)

frontend/src/components/combobox/combobox.ts

@@ -174,8 +174,24 @@ export class YjCombobox extends LitElement {
         // fire first.
         requestAnimationFrame(() => {
             this.open = false;
-            // Restore display text to the confirmed value.
-            this.filterText = this.value;
+
+            // Commit free-form text: if the user typed something that
+            // isn't in the option list, accept it as the value anyway.
+            const typed = this.filterText.trim();
+            if (typed && typed !== this.value) {
+                this.value = typed;
+                this.filterText = typed;
+                this.dispatchEvent(
+                    new CustomEvent('combobox-change', {
+                        bubbles: true,
+                        composed: true,
+                        detail: { value: typed },
+                    }),
+                );
+            } else {
+                // Restore display text to the confirmed value.
+                this.filterText = this.value;
+            }
         });
     }
 
@@ -211,6 +227,11 @@ export class YjCombobox extends LitElement {
                 ) {
                     e.preventDefault();
                     this.selectOption(opts[this.highlightedIndex]!);
+                } else if (this.filterText.trim()) {
+                    // Commit free-form text on Enter even without a
+                    // highlighted option.
+                    e.preventDefault();
+                    this.selectOption(this.filterText.trim());
                 }
                 break;