feat: add session rename with swipe-left action (#290)

[ascott]

Summary

Adds the ability to rename active sessions from the sessions list. Users swipe left on an active session to reveal a Rename button alongside the existing Archive button. Custom names are stored locally via MMKV and persist across app restarts and sync updates.

• Swipe left on any active session to see Rename and Archive actions
• Tapping Rename opens a prompt pre-filled with the current custom name (or empty with the default name as placeholder)
• Clearing the name resets to the default (summary text or last path segment)
• Custom names are preserved across sync updates and cleaned up on session delete
• Adds maxLength support to Modal.prompt (enforced on iOS via custom modal)
• 49 new tests covering utils, persistence, and store actions
• Translations added for all 11 languages

Implementation

• Local-only persistence: Follows the existing draft/permissionMode pattern — stored in Zustand state, persisted to MMKV, restored on app launch, preserved during applySessions merge
• UI trigger: Swipe-left on active sessions reveals both Rename (grey, pencil icon) and Archive (red, archive icon) buttons
• Name resolution: getSessionName() returns customName || summaryText || lastPathSegment || "Unknown"
• Whitespace normalization: Leading/trailing whitespace is trimmed; empty strings reset to default

Test plan

• Swipe left on an active session — should show Rename and Archive buttons
• Tap Rename — prompt appears with placeholder showing default name
• Enter a name and confirm — session title updates immediately
• Clear the name and confirm — reverts to default name
• Force quit and reopen — custom name persists
• Verify all 49 tests pass (yarn test --run)

Screen recording

Screen.Recording.2026-02-23.at.4.16.51.PM.mov

Closes #290