feat(sidebar): add a favorite/pin toggle for connections

[Asgabani]

Closes #694.

A star toggle on each connection row in the sidebar, persisted to a new favorite_connections storage collection. Favorited connections render together in their own group above the rest of the list, which keeps exactly the order and behaviour it always had — toggling a favorite only ever pulls entries out of the regular list, never reorders or filters what remains.

Why a separate id set, not a field on DatabaseConnection: a managed:true connection is always taken fresh from the server on every load, so a field on the connection object itself would be silently discarded on reload for exactly the connections a user is most likely to want to favorite. A separate id list favorites correctly regardless of who owns the connection, and a duplicated connection (new id) doesn't inherit the original's favorite status for free.

Implementation: useFavoriteConnections is built on useSyncExternalStore rather than an effect that reads storage and calls setState — favorite_connections is exactly that: state living outside React, mutated by the storage facade — so a favorite pulled down from the server, or toggled from another mounted instance of the hook, is reflected without a synchronous setState-in-effect render cascade (caught by react-hooks/set-state-in-effect on my first draft). The new collection is wired into every place that treats STORAGE_COLLECTIONS as the full set (server-sync pull path, the collection-data switch), alongside the existing dismissed_seeds entry.

Testing

• bun run format, lint, typecheck, knip, chart:check, channels:showcase:check, readme:check, security:check, and build all pass.
• bun run test:coverage + coverage:check: 100.00% (47133/47133 lines) on the merged report. Every file this PR touches is individually at 100%, including the SSR-only getServerSnapshot branch (exercised via ReactDOMServer.renderToString, matching the existing pattern in use-line-numbers-preference.test.ts).
• bun run test itself still fails locally — 195 pre-existing failures, all either Helm chart tests (no helm binary in my environment) or DB-provider integration tests needing a live database. Verified identical on a clean, unmodified checkout via git stash before starting. None are in a file this PR touches.

[cevheri]

thanks and welcome @Asgabani
I’m working on PR #811 right now, which includes some big changes to the schema/objects explorer(nosql databases test remaining)

After that, I’ll do a detailed local test your PR and give feedback

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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