fix(web): complete recovery navigation and GitHub connection workflows

[Qiyuanqiii]

Closes #292.

Continuity Fork/Resume and Workspace checkpoint Fork previously updated the retired selected-Run store without moving V2. They now open the exact returned Run without inheriting the source Thread binding, preserve browser Back, and refresh saved records, workspaces, and all active Thread search/page caches. Completion after a navigation change refreshes data without replacing the current page.

GitHub Review now distinguishes creating a connection from editing one. Updates carry the selected connection ID and generation, preserve existing configuration, and retain drafts on conflicts. Confirmed disconnect removes the selected connection's current local credential, refreshes shared-credential status, and clears device-flow/review state. The dialog describes the existing connection-scoped API; it does not claim remote grant revocation or an exact old credential-name CAS.

Async results stay bound to their original Run, connection and client. Retained review previews keep their original PR, snapshot, connection generation and credential binding across approval navigation; changed or missing bindings require a new preview. Failed status refreshes cannot turn cached evidence into an executable write.

The existing Go APIs and authority checks remain in charge, following ADR 0115, 0118 and 0123. This is the recovery/connection slice of the frontend rebuild, not acceptance of the remaining backlog.

Validation at 198aff354d3bb38f09ea7305d8542b314c69e796:

• Complete frontend suite: 175 files / 1,680 tests passed.
• Applicable CI passed: TypeScript console, Go checks and the Go control-plane gate. Unaffected jobs were skipped by the existing classifier.
• Combined locally with fix(web): align approval readiness and task capability entries #288 at 65de06592d96aaa51e10ba9e0bea46009deac2ea: 176 files / 1,720 frontend tests and TypeScript passed; the branches merge without conflicts.
• 15 real V2 composition regressions cover all three recovery actions, browser Back, stale completion, exact Run scope, and multi-page/search cache refreshes.
• 24 GitHub panel regressions cover generation conflicts, local disconnect, shared credentials, stale client/results, and actual approval unmount/remount with PR/snapshot/generation changes.
• TypeScript and production build passed; npm run check:api passed.
• Focused independent review findings were fixed and rechecked. git diff --check passed.

Tests use isolated local state and API fixtures; this is not a real GitHub OAuth or remote-write smoke. The existing large-chunk production-build warning remains.