feat: non-destructive lock recovery for pushed branches (Closes #440)

Adds structured issue-branch ownership parsing, wires it into lock adoption
and gitea_lock_issue validation, documents the restart recovery workflow, and
adds regression tests for adoption, durable create_pr resolution, and open-PR
blocking without remote branch deletion.

Built on keyed persistent lock store and own-branch adoption (#443 / #442).

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

tests/test_issue_branch_ownership.py

@@ -0,0 +1,36 @@
+"""Structured issue branch ownership (#440)."""
+import sys
+import unittest
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+import issue_branch_ownership as ibo  # noqa: E402
+
+
+class TestIssueBranchOwnership(unittest.TestCase):
+    def test_canonical_branch_parses_issue_number(self):
+        self.assertEqual(
+            ibo.parse_issue_branch("feat/issue-420-server-code-parity"),
+            420,
+        )
+
+    def test_prefix_variants_supported(self):
+        for prefix in ("fix", "feat", "docs", "chore"):
+            branch = f"{prefix}/issue-440-lock-recovery"
+            self.assertTrue(ibo.branch_belongs_to_issue(branch, 440))
+
+    def test_substring_false_positive_rejected(self):
+        self.assertFalse(
+            ibo.branch_belongs_to_issue("feat/my-issue-420-backport", 420)
+        )
+        self.assertFalse(ibo.branch_belongs_to_issue("release/issue-420-hotfix", 420))
+
+    def test_different_issue_number_rejected(self):
+        self.assertFalse(
+            ibo.branch_belongs_to_issue("feat/issue-421-server-code-parity", 420)
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()