docs: add brew trust step to all Homebrew install snippets

Homebrew 6+ refuses to load formulae from untrusted third-party taps
(Error: Refusing to load formula gitlawb/tap/gl from untrusted tap);
interactive users get stuck and non-interactive agents hard-fail.
brew trust gitlawb/tap after tapping is now part of every install
snippet (agents.md, quickstart.md, skill.md, tap README).

Author: kevincodex1

public/docs/agents.md

@@ -17,7 +17,7 @@ Any one of these; all install both `gl` and `git-remote-gitlawb`:
 
 ```sh
 npm install -g @gitlawb/gl          # npm
-brew tap gitlawb/tap && brew install gl   # Homebrew
+brew tap gitlawb/tap && brew trust gitlawb/tap && brew install gl   # Homebrew (6+ requires trusting third-party taps)
 curl -sSf https://gitlawb.com/install.sh | sh   # curl installer
 ```
 

public/docs/quickstart.md

@@ -10,8 +10,8 @@ Pick one:
 # npm
 npm install -g @gitlawb/gl
 
-# Homebrew (macOS / Linux)
-brew tap gitlawb/tap && brew install gl
+# Homebrew (macOS / Linux) — brew 6+ requires trusting third-party taps
+brew tap gitlawb/tap && brew trust gitlawb/tap && brew install gl
 
 # curl installer (macOS / Linux)
 curl -sSf https://gitlawb.com/install.sh | sh

public/skill.md

@@ -49,6 +49,7 @@ npm install -g @gitlawb/gl
 
 ```sh
 brew tap gitlawb/tap
+brew trust gitlawb/tap   # Homebrew 6+ requires trusting third-party taps
 brew install gl
 ```