Add container-native scheduled task system with timezone support

Introduces a cron-based scheduler that lets Claude set up recurring and
one-time tasks inside containers. Tasks run as separate Claude Code agents
and persist across container recreation via the named volume.

New files:
- container/triple-c-scheduler: CLI for add/remove/enable/disable/list/logs/run/notifications
- container/triple-c-task-runner: cron wrapper with flock, logging, notifications, auto-cleanup

Key changes:
- Dockerfile: add cron package and COPY both scripts
- entrypoint.sh: timezone setup, cron daemon, crontab restore, env saving
- container.rs: init=true for zombie reaping, TZ env, scheduler instructions, timezone recreation check
- image.rs: embed scheduler scripts in build context
- app_settings.rs + types.ts: timezone field
- settings_commands.rs: detect_host_timezone via iana-time-zone crate
- SettingsPanel.tsx: timezone input with auto-detection

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src-tauri/src/lib.rs

@@ -84,6 +84,7 @@ pub fn run() {
             commands::settings_commands::pull_image,
             commands::settings_commands::detect_aws_config,
             commands::settings_commands::list_aws_profiles,
+            commands::settings_commands::detect_host_timezone,
             // Terminal
             commands::terminal_commands::open_terminal_session,
             commands::terminal_commands::terminal_input,