chore: address code review feedback

Address suggestions from gemini-code-assist and coderabbit-ai:

Logging Improvements:
- Remove excessive debug logging from ClaudeProvider
- Remove sensitive environment variable logging (API key length, HOME, USER)
- Remove verbose per-message stream logging from AgentService
- Remove redundant SDK options logging
- Remove watchdog timer logging (diagnostic tool)

Documentation:
- Update JSDoc example in ClaudeMdSettings to include sandbox props

Persistence Fix:
- Add enableSandboxMode to syncSettingsToServer updates object
- Ensures sandbox setting is properly persisted to server storage

This reduces log volume significantly while maintaining important
error and state transition logging.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/ui/src/hooks/use-settings-migration.ts

@@ -224,6 +224,7 @@ export async function syncSettingsToServer(): Promise<boolean> {
       enhancementModel: state.enhancementModel,
       validationModel: state.validationModel,
       autoLoadClaudeMd: state.autoLoadClaudeMd,
+      enableSandboxMode: state.enableSandboxMode,
       keyboardShortcuts: state.keyboardShortcuts,
       aiProfiles: state.aiProfiles,
       projects: state.projects,