feat: add session authorization mode configuration (#446)

Add approvals.mode configuration to allow users to enable/disable
session operation authorization. Mode can be 'off' (no auth) or 'manual'
(require auth). Changes trigger automatic gateway restart for config
to take effect.

- Add ApprovalConfig type with mode: 'off' | 'manual'
- Add approvals section to settings store
- Add session authorization toggle in SessionSettings UI
- Add approvals to PLATFORM_SECTIONS for auto-restart
- Add i18n support for all 8 languages

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/client/src/i18n/locales/en.ts

@@ -526,6 +526,8 @@ export default {
       liveMonitorHumanOnly: 'Live monitor: show human sessions only',
       liveMonitorHumanOnlyHint: 'Hide sub-agent/session monitor noise in the Live monitor by default',
       atHourHint: 'Reset session at this hour daily',
+      requireAuth: 'Session Authorization',
+      requireAuthHint: 'Require authorization for session operations',
     },
     privacy: {
       redactPii: 'Redact PII',