cask: document quarantine removal, --no-quarantine no longer exists

Recent Homebrew removed the --no-quarantine option entirely, so the
install docs and cask now instruct clearing the quarantine attribute
with xattr after install/upgrade. The cask prints it as a caveat at
install time.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Casks/brewbar.rb

@@ -16,4 +16,11 @@ cask "brewbar" do
     "~/Library/Application Support/BrewBar",
     "~/Library/Preferences/com.MaxSoch.BrewBar.plist",
   ]
+
+  caveats <<~EOS
+    BrewBar is not notarized. On any Mac that did not build it, clear the
+    quarantine flag after install or upgrade, or Gatekeeper will block it:
+
+      xattr -dr com.apple.quarantine /Applications/BrewBar.app
+  EOS
 end

RELEASING.md

@@ -55,11 +55,17 @@ together). The git tag and zip filename must match it exactly: version `1.1`
 ## Notes
 
 - The app is signed with an Apple *Development* certificate, not notarized.
-  Installs need `--no-quarantine`; without it Gatekeeper blocks the app.
+  Recent Homebrew removed the `--no-quarantine` option, so on any Mac that
+  did not build the app, clear the quarantine flag after install/upgrade
+  (the cask prints this reminder as a caveat):
+  ```
+  xattr -dr com.apple.quarantine /Applications/BrewBar.app
+  ```
 - `dist/` and `build/` are gitignored — release zips live only in Forgejo
   releases, never in git.
 - First install on a new machine:
   ```
   brew tap maxsoch/brewbar https://forgejo.socheleau.fr/maxsoch/BrewBar.git
-  brew install --cask --no-quarantine maxsoch/brewbar/brewbar
+  brew install --cask maxsoch/brewbar/brewbar
+  xattr -dr com.apple.quarantine /Applications/BrewBar.app
   ```