ci: switch to commit-message triggers (replace issue_comment)

issue_comment triggers had two problems: Gitea did not reliably fire
them, and the refs/pull/N/head checkout was fragile.  Commit-message
keywords are simpler and guaranteed to work on any push event.

Trigger keywords (add anywhere in the commit message):
  /test-cgal      → CGAL test suite (277 tests, LOW_MEMORY_BUILD)
  /quality-gates  → license/codespell/shellcheck/cgal-conventions
  /docs           → Doxygen build + warning summary
  /links          → Markdown internal link check

test-fast still runs on every push (no keyword needed).

All `issue_comment` event handlers and `refs/pull/N/head` checkouts
removed from all three workflow files.  review/** added to push branch
filters so this PR branch triggers normally.

CLAUDE.md CI table updated.

/test-cgal /quality-gates

.gitea/workflows/doc-build.yaml

@@ -1,11 +1,19 @@
 name: API Docs
 
-# Trigger: write "/docs" as a comment on any pull request.
-# Also available via workflow_dispatch for manual runs outside a PR context.
+# Trigger: include "/docs" anywhere in the commit message.
+#
+#   git commit -m "docs: update API examples /docs"
+#
+# Also available via workflow_dispatch for manual runs.
 
 on:
-  issue_comment:
-    types: [created]
+  push:
+    branches:
+      - main
+      - dev
+      - "claude/**"
+      - "feature/**"
+      - "review/**"
   workflow_dispatch: {}
 
 # ─────────────────────────────────────────────────────────────────────────────
@@ -14,25 +22,18 @@ on:
 # Generates Doxygen HTML from the public headers and reports warning
 # statistics.  Does NOT block merges: `continue-on-error: true` ensures
 # warnings or extraction issues never fail.
-#
-# Trigger: "/docs" PR comment (or workflow_dispatch for manual runs).
-# Checkout uses refs/pull/N/head when triggered via comment.
 # ─────────────────────────────────────────────────────────────────────────────
 jobs:
   doc-build:
     if: |
       github.event_name == 'workflow_dispatch' ||
-      (github.event_name == 'issue_comment' &&
-       github.event.issue.pull_request != null &&
-       contains(github.event.comment.body, '/docs'))
+      contains(github.event.head_commit.message, '/docs')
     runs-on: eulernest
     container:
       image: git.eulernest.eu/conformallab/ci-cpp:latest
     continue-on-error: true   # never block the merge
     steps:
       - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event_name == 'issue_comment' && format('refs/pull/{0}/head', github.event.issue.number) || github.ref }}
 
       - name: Generate API documentation
         run: doxygen Doxyfile 2>&1 | tee doxygen.log