Improve feature search UX, add dark mode, and update deps

[riverar]

Changes:

• Added dark mode with a theme switcher
• Better sorting: match position + suffix length
• Search terms now added to URL for easy sharing
• Branch switching auto-updates search results
• Improved search result view on mobile
• Updated Node.js dependency

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Files not reviewed (1)

• web/features/tsconfig.json: Language not supported

Comments suppressed due to low confidence (4)

web/features/src/app.tsx:167

• The initialization of the query state with params.query! ?? '' might cause an error if params.query is undefined. It should be initialized with params.query ?? '' instead.

const [query, setQuery] = useState(params.query! ?? '');

web/features/src/worker/search.ts:100

• [nitpick] The variable name 'query_lower' is ambiguous. It should be renamed to 'queryLower' for better readability.

const query_lower = query.toLowerCase();

web/features/src/worker/search.ts:101

• [nitpick] The variable name 'a_lower' is ambiguous. It should be renamed to 'nameALower' for better readability.

const a_lower = a.name.toLowerCase();

web/features/src/worker/search.ts:102

• [nitpick] The variable name 'b_lower' is ambiguous. It should be renamed to 'nameBLower' for better readability.

const b_lower = b.name.toLowerCase();

[riverar]

@tim-weis Heads up Tim, added a few of the items you requested! (e.g., better result sort)