feat: implement session rename with SQLite storage (#413)

* feat: implement session rename with SQLite storage (closes #72, fixes #358)

- Add session_names table to store custom display names per provider
- Add PUT /api/sessions/:sessionId/rename endpoint
- Replace stub updateSessionSummary with real API call
- Apply custom names across all providers (Claude, Codex, Cursor)
- Fix project rename destroying config (spread merge instead of overwrite)
- Thread provider parameter through sidebar component chain
- Add i18n error messages for rename failures (en, ja, ko, zh-CN)

* fix: address CodeRabbit review feedback for session rename

- Log migration errors instead of swallowing them silently (db.js)
- Add try/catch to applyCustomSessionNames to prevent getProjects abort
- Move applyCustomSessionNames to db.js as shared helper (DRY)
- Fix Cursor getSessionName to check session.summary for custom names
- Move edit state clearing to finally block in updateSessionSummary
- Sanitize sessionId, add 500-char summary limit, validate provider whitelist
- Remove dead applyCustomSessionNames call on empty manual project sessions

* fix: reject sessionId on mismatch instead of silent normalization

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* fix: enable rename for all providers, add Gemini support, clean up orphans

- Enable rename UI (pencil icon) for Codex, Cursor, and Gemini sessions
- Keep delete button hidden for Cursor (no backend delete endpoint)
- Add 'gemini' to VALID_PROVIDERS and hoist to module scope
- Add sessionNamesDb.deleteName on session delete (claude, codex, gemini)
- Fix token-usage endpoint sessionId mismatch validation
- Remove redundant try/catch in sessionNamesDb methods
- Let session_names migration errors propagate to outer handler

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: Haileyesus <118998054+blackmammoth@users.noreply.github.com>

src/utils/api.js

@@ -77,6 +77,11 @@ export const api = {
     authenticatedFetch(`/api/projects/${projectName}/sessions/${sessionId}`, {
       method: 'DELETE',
     }),
+  renameSession: (sessionId, summary, provider) =>
+    authenticatedFetch(`/api/sessions/${sessionId}/rename`, {
+      method: 'PUT',
+      body: JSON.stringify({ summary, provider }),
+    }),
   deleteCodexSession: (sessionId) =>
     authenticatedFetch(`/api/codex/sessions/${sessionId}`, {
       method: 'DELETE',