fix(profiles): canonical reconciler ops and guard raw branch delete (#687)

Address REQUEST_CHANGES on PR #688:

- migrate_profiles: emit fully canonical reconciler/author/reviewer defaults;
  canonicalize explicit ops; fail if reconciler loses required pr.close/read
- gitea_delete_branch: deny reconciler (and non-author roles); refuse
  preservation/protected branches before any API call
- gitea_cleanup_merged_pr_branch: require reconciler role only; block
  preservation/evidence branches via branch_cleanup_guard
- docs: end-to-end operator runbook for profile migrate/apply/reconnect/cleanup
- tests: migration canonicalization, idempotency, raw-delete denial, guarded
  cleanup success and unmerged/preserve rejections

Closes #687.

branch_cleanup_guard.py

@@ -7,6 +7,19 @@ from typing import Any
 
 PROTECTED_BRANCHES = frozenset({"master", "main", "dev"})
 
+# Evidence / preservation branches must never be removed by cleanup tools
+# (e.g. chore/issue-681-preserve-review-session-wip).
+_PRESERVATION_MARKERS = ("preserve", "preservation", "evidence")
+
+
+def is_preservation_or_evidence_branch(branch: str | None) -> bool:
+    """Return True when *branch* is a preservation/evidence ref that must stay."""
+    if not branch:
+        return False
+    name = str(branch).lower()
+    return any(marker in name for marker in _PRESERVATION_MARKERS)
+
+
 _RAW_BRANCH_DELETE_PATTERNS = (
     re.compile(r"\bgit(?:\s+-C\s+\S+)?\s+branch\s+-[dD]\b[^\n\r]*", re.I),
     re.compile(r"\bgit(?:\s+-C\s+\S+)?\s+push\b[^\n\r]*\s--delete\b[^\n\r]*", re.I),
@@ -72,6 +85,11 @@ def assess_merged_pr_branch_cleanup(
         reasons.append("PR head branch is missing")
     if head_branch in protected:
         reasons.append(f"branch '{head_branch}' is protected")
+    if is_preservation_or_evidence_branch(head_branch):
+        reasons.append(
+            f"branch '{head_branch}' is a preservation/evidence branch and "
+            "cannot be deleted through merged-PR cleanup"
+        )
     if head_branch in open_pr_heads:
         reasons.append("an open PR still references this head branch")
     if head_on_target is False: