feat(hooks): add ticket-gate Crush hook — enforce ticket-first work

Mechanically enforces the Agent Authority policy: blocks all modifying
operations (bash, edit, write, multiedit) until an active ticket is set
via: echo '#NNN' > .crush/active-ticket

Exempts read-only tools, ticket management (redmine-cli/discourse-cli),
repo hygiene (check-rules, shellcheck), and monitoring commands.

Also: un-ignore .crush/crush.json so the hook config is tracked in git.

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

.gitignore

@@ -1,5 +1,9 @@
-# Crush internal state
-.crush/
+# Crush internal state (track crush.json config, ignore session data)
+.crush/crush.db
+.crush/crush.db-*
+.crush/logs/
+.crush/memory/
+.crush/active-ticket
 
 # OS/editor
 .DS_Store