feat: branch/PR naming standard CI check

Composite action that validates head branch and PR title against the
fritzlab naming standard (role/bug-id/kebab + [bug-id] titles).
Always exits 0 (warn-only) until the Bugs system is live.

- check.sh: validation logic (branch form, title form, bug-id cross-check)
- action.yaml: composite action wrapping check.sh
- tests/run: 20-case test matrix (valid/invalid/chore/mismatch/dfritz)
- .gitea/workflows/test.yaml: CI that runs the test suite

Closes fritzlab/agenthub#559

action.yaml

@@ -0,0 +1,38 @@
+name: Check branch/PR naming
+description: |
+  Validates that a PR's head branch and title follow the fritzlab naming
+  standard. Always exits 0 — warn-only until the Bugs system is live.
+  Produces WARN log lines for any violation.
+
+  Standard:
+    branch:   <role>/bug-<id>/<kebab>   e.g. dev/bug-x7k2m9/fix-terminal-resize
+    chore:    chore/<kebab>              bug-less trivia only
+    title:    [bug-<id>] Description    (chore PRs: no [bug-id] prefix)
+
+  Role must be a roster handle: dev | ux | ops | security | perf | architect | support
+  Break-glass: PRs authored by dfritz are exempt.
+
+inputs:
+  head-branch:
+    description: Head branch name — github.head_ref on pull_request events.
+    required: true
+  pr-title:
+    description: PR title — github.event.pull_request.title.
+    required: true
+  pr-author:
+    description: |
+      PR author login — github.event.pull_request.user.login.
+      dfritz is exempt from all checks.
+    required: false
+    default: ''
+
+runs:
+  using: composite
+  steps:
+    - name: Validate naming
+      shell: bash
+      env:
+        HEAD_BRANCH: ${{ inputs.head-branch }}
+        PR_TITLE: ${{ inputs.pr-title }}
+        PR_AUTHOR: ${{ inputs.pr-author }}
+      run: bash "${{ github.action_path }}/check.sh"