Extract vault management (useVaultSwitcher), git history loading
(useGitHistory), dialog state (useDialogs), and keyboard/command
setup (useAppCommands) into dedicated hooks. App.tsx code health
improves from 8.95 to 10.0 — all extracted hooks also score 10.0.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
