feat(mobile): add Haptic feedback preference

[iscekic]

Request

In the mobile app preferences screen, add a 'Haptic feedback' section with three options: Off, Light, and Full. The selected option persists across app launches and takes effect immediately when tapped.

Changelog for users

• The Preferences screen shows a new "Haptic feedback" section with three options: Off, Light, and Full.
• Tapping an option applies it immediately. Off stops haptic feedback, Light softens it, and Full keeps full feedback.
• The selected option persists across app launches and restores when the app reopens.

Changelog for maintainers

• Added a @/lib/haptics gate. All haptic call sites now import it instead of expo-haptics, and the gate reads a module-scope strength on every call.
• Off turns selection, impact, and notification calls into no-ops. Light caps impacts at the softest tick and downgrades notification buzzes to a selection tick. Full forwards every call unchanged.
• Added @/lib/hooks/use-haptic-preference, a SecureStore preference under key haptic-strength with default full. preloadHapticPreference() runs in the root layout at app start and mirrors the stored value into the gate.
• Added hapticFeedback, hapticFull, and hapticLight to every locale catalog. hapticLight is a screen-reader label that interpolates two other keys and is now in the English-identical allowlist.
• SegmentedControl now accepts a per-option accessibilityLabel. The haptic Light option uses it to disambiguate from the Appearance Light radio for screen readers.
• Added unit and mounted tests for the gate, the hook store-and-gate mirror, the segmented-control labels, and the preferences screen. The hook test covers the save-failure toast path.
• Review risk: the gate holds module-scope state, and the hook arms its mirror subscription only once. Check that the load-once flag stays correct across re-mounts.

E2E proof

Follow-ups (not changed here)

• Preferences — tab bar covers the Language row (e4.png).
• not proved live: Android: the VM proof section did not launch; proved on iOS only