docs: repair the Homebrew install, broken by Homebrew 6

[Periicles]

The install command we publish in the README and on the landing page does not work any more:

$ brew install --cask --no-quarantine notchbar
Error: invalid option: --no-quarantine

Homebrew removed the flag (ba25213c81, July 2026) and now quarantines every cask unconditionally. Dropping the flag is not enough — the installed bundle still carries com.apple.quarantine (0381;…), and NotchBar is ad-hoc signed, so Gatekeeper blocks the first launch. Both docs claimed the opposite: "they install and launch with no prompt at all."

What changes

• The Homebrew block gains xattr -dr com.apple.quarantine /Applications/NotchBar.app, the step that now does what --no-quarantine used to.
• Only the curl route is still described as prompt-free — curl sets no flag, so that claim was and stays true.
• The Updating table repeats the xattr line. Homebrew carries an unquarantined app forward across an upgrade only while its signing identity is unchanged, and an ad-hoc signature is designated by the binary cdhash, which every build changes — so the release decision lands on :signer_changed and the new copy is quarantined again.
• Landing page updated in both locales; "unsigned" reworded to "not notarized", which is what Gatekeeper actually objects to (the app is signed, ad-hoc).
• Changelog compare links were stale at v0.3.0, leaving the 0.3.1 and 0.3.2 headings pointing at nothing.

Verification

The documented sequence was replayed from a clean uninstall on Homebrew 6.0.20:

brew install --cask notchbar         -> /Applications/NotchBar.app, quarantined 0381
xattr -dr com.apple.quarantine ...   -> No such xattr
codesign --verify --strict           -> exit 0 (signature intact)
open -a /Applications/NotchBar.app   -> process running, no Gatekeeper prompt

swift build and swift test (102 tests) pass — no source file is touched.

Note

This is a workaround, not a fix for the root cause. Every route that sets a quarantine flag now costs the user a step, which only notarization removes. Worth reconsidering whether the tap cask should carry a caveats stanza with the same line, so the step is visible to people who never read the README.