feat(author-workflow): enforce exact issue lock before branch/commit/push/PR (Issue #204)

Recreation of the #204 work from closed PR #205 (invalid provenance), rebuilt
cleanly on master under the prgs author identity with no PR #203 content:

- Add gitea_lock_issue MCP tool: locks exactly one issue to its branch name,
  fails closed on branch/issue-number mismatch and on issues already tied to
  an open PR (by head branch or Closes/Fixes reference).
- gitea_create_pr now requires the issue lock: head must match the locked
  branch, title/body must contain Closes/Fixes #<locked issue> exactly, and
  ambiguous references (equivalent / related / same as) are rejected.
- scripts/worktree-start refuses to create an issue-linked worktree unless the
  lock file exists and matches the requested branch.
- assess_controller_handoff rejects handoffs whose selected issue / opened PR
  fields carry multiple numbers or fuzzy equivalence wording.
- Tests: TestIssueLocking (lock + create_pr gates), handoff exact-reference
  tests, worktree-start lock coverage.

Closes #204

Co-Authored-By: Claude Fable 5 <[email protected]>

tests/test_review_proofs.py

@@ -838,6 +838,40 @@ class TestControllerHandoff(unittest.TestCase):
         self.assertEqual(result["verdict"], "incomplete")
         self.assertIn("No review/merge confirmation", result["missing_fields"])
 
+    def test_author_role_rejects_equivalent_or_multiple_issues(self):
+        # 1. equivalent reference blocked
+        incomplete_eq = self.BASE_HANDOFF + "\n" + "\n".join([
+            "- Selected issue: Issue #194 / #196 equivalent",
+            "- Claim/comment status: comment-claimed",
+            "- PR number opened: #999",
+            "- No review/merge: confirmed",
+        ])
+        res = assess_controller_handoff(incomplete_eq, role="author")
+        self.assertEqual(res["verdict"], "incomplete")
+        self.assertIn("Selected issue", res["missing_fields"])
+
+        # 2. multiple issues blocked
+        incomplete_multi = self.BASE_HANDOFF + "\n" + "\n".join([
+            "- Selected issue: #194, #196",
+            "- Claim/comment status: comment-claimed",
+            "- PR number opened: #999",
+            "- No review/merge: confirmed",
+        ])
+        res = assess_controller_handoff(incomplete_multi, role="author")
+        self.assertEqual(res["verdict"], "incomplete")
+        self.assertIn("Selected issue", res["missing_fields"])
+
+    def test_author_role_rejects_fuzzy_pr_number(self):
+        incomplete_pr = self.BASE_HANDOFF + "\n" + "\n".join([
+            "- Selected issue: #196",
+            "- Claim/comment status: comment-claimed",
+            "- PR number opened: PR #203 / #204 equivalent",
+            "- No review/merge: confirmed",
+        ])
+        res = assess_controller_handoff(incomplete_pr, role="author")
+        self.assertEqual(res["verdict"], "incomplete")
+        self.assertIn("PR number opened", res["missing_fields"])
+
     def test_inventory_role_requires_inventory_fields(self):
         complete = self.BASE_HANDOFF + "\n" + "\n".join([
             "- Repositories checked: Gitea-Tools, mcp-control-plane",