[codex] Restore logout confirmation

[Uarmagan]

What changed

• Adds a logout confirmation dialog for the global Z shortcut and command-palette logout action.
• Keeps logout itself in the existing logout hook, but routes shortcut and palette logout through the confirmation step first.
• Improves the shared overlay panel so the confirmation behaves like a real dialog for focus and labels.

Why

PR #1794 removed the old /logout route. That route used to require a separate Signout button, but after it was removed the Z shortcut called logout immediately. This restores the missing user consent step without bringing the route back.

Validation

• bun test src/components/LogoutConfirmation/LogoutConfirmationDialog.test.tsx src/views/Week/hooks/shortcuts/useGlobalShortcuts.test.tsx src/common/hooks/useLogoutCmdItems.test.ts src/auth/compass/hooks/useLogout.test.ts
• bun type-check
• bun run build:web
• Focused Biome check on the touched files
• Browser smoke against a fresh local build: Z opens the confirmation, Cancel keeps the user signed in, and Log out clears auth state

Notes

• Full bun lint is currently blocked by unrelated local changes under skill folders; the touched files pass focused lint.