fix: remove post_install from Homebrew formula

Homebrew sandboxes post_install so it can't write to ~/Library/LaunchAgents.
Users run awake install themselves — this is the standard Homebrew pattern
for services that need user-level permissions.

fix: guided notification setup and codesign fix

- Re-sign Awake.app with codesign after modification so macOS Tahoe
  accepts notifications from the bundle
- Open System Settings to Awake notification page during install
- Wait for user to enable notifications before sending welcome message
- Suppress daemon startup notification during fresh install to avoid
  stomping the welcome notification
- Fresh install: "Thanks for the download! Support FOSS..."
- Re-install: "Awake is ready"

feat: daemon startup notification and auto-workday sessions

Daemon now sends a notification on startup so you know it's running
after a reboot. New auto_workday config option (default true on fresh
installs) makes the daemon automatically start a workday session on
configured days during work hours. Toggleable in TUI options view.

ci: add Homebrew formula to repo, auto-update on release

Formula lives at Formula/awake.rb in the same repo. Release workflow
now computes SHA256 hashes and commits updated formula after each
tagged release. Users install via:
  brew tap VolksRat71/awake https://github.com/VolksRat71/awake
  brew install awake