feat: switch-while-running, startup settings and more

[rushiranpise]

Description:

Summary

Bundles 6 features + UI polish into a single branch from scratch.

What's changed

Switch accounts while Codex is running
The Switch button no longer disables when Codex is running. Clicking it shows a confirmation dialog ("unsaved work may be lost"), force-kills Codex processes, then switches. The backend switch_account command accepts a new optional force parameter to bypass the running-process guard.

"Open Codex" in both tray menus
Added to the native right-click menu (between "Open Codex Switcher" and "Quit") and to the React tray popup footer.

Open Codex automatically after switching
New "Open Codex after switch" toggle in the Settings dropdown. When enabled, Codex launches after every successful account switch.

Launch at Login / Start Minimized
Two new toggles in the Settings dropdown (Tauri only). Launch at Login uses tauri-plugin-autostart. Start Minimized hides the main window on startup so the app runs silently in the tray.

Warmup and refresh failure details

• Warm-up all: toast now lists each failed account name instead of just a count. Multi-line toasts stay for 8 s.
• Refresh all: shows per-account errors on failure instead of always showing a generic success message.

Active account pinned at top in both tray menus
Both the native right-click menu and the React tray popup always show the active account first, with a separator below it.

UI polish

• Switch button: whitespace-nowrap, label becomes "Switch & Close" when Codex is running
• "Account" dropdown renamed to "Settings"

Configurable Auto warm-up and usage refresh interval

• New picker in the Settings dropdown to control how often usage bars are refreshed. Presets: 30 s, 1 min (default), 5 min, 10 min, 30 min. A custom minutes input accepts any value from 1–60 min. Setting persists in localStorage and takes effect immediately.

Testing

• Built Windows EXE successfully (Codex Switcher_0.2.9_x64-setup.exe)
• cargo fmt applied; cargo check passes (warnings only, no errors)