Follow-up: remove local thread-name override persistence

[Dimillian]

Motivation

• Local per-thread name overrides stored in localStorage could permanently mask thread/name/updated events and list refreshes, causing the UI to diverge from Codex thread state.
• Make the Codex thread name the single source of truth and keep renames as optimistic UI updates backed by thread/name/set to Codex.

Description

• Stop persisting thread renames to codexmonitor.threadCustomNames by removing calls to saveCustomName and local customNamesRef updates from useThreads.renameThread (src/features/threads/hooks/useThreads.ts).
• Simplify useThreadStorage so it no longer hydrates or listens to a custom-names localStorage key and instead exposes getCustomName that always returns undefined (src/features/threads/hooks/useThreadStorage.ts).
• Update tests to reflect the new behavior by removing expectations around custom-name persistence and by adjusting an integration test to assert that names are reflected from Codex/list responses (src/features/threads/hooks/useThreadStorage.test.tsx, src/features/threads/hooks/useThreads.integration.test.tsx).
• Clean up related imports and refs where the local custom-name API was removed.

Testing

• Ran targeted unit/integration tests: npm run test -- src/features/threads/hooks/useThreadStorage.test.tsx src/features/threads/hooks/useThreads.integration.test.tsx, and both test files passed (30 tests total passed).
• Ran type checking with npm run typecheck and tsc --noEmit completed successfully.

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Codex Task

[Dimillian]

@codex review

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Keep manual rename signal for title autogeneration guard

Returning undefined unconditionally from getCustomName removes the cancellation signal that useThreadTitleAutogeneration.onUserMessageCreated relies on before and after generateRunMetadata to avoid overwriting user-renamed threads. In the race where a user renames a thread while metadata generation is in flight, the post-await guard no longer trips and renameThread(..., title) can clobber the manual name when the async call resolves; this is a regression from the previous behavior where renameThread immediately updated custom-name state.

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