fix(projection): a stamped slug counts as retired even if the flag is clear

Six rows were resurrected before the previous fix landed: tombstoned slug,
cleared retirement flag, sitting beside the correct record derived from the
same file. Nothing can see them. They are not retired, so they are not stale;
they path-match their own file, so every reset reports `noop` and they persist
indefinitely.

The stamp in the slug is itself evidence that a retirement happened, so a row
carrying the mark with a cleared flag is a contradiction to repair rather than
a live record. Such a row is now skipped by the heuristics like any retired
one, which makes it visible as a retirement candidate again.

747 pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 2583210@bnt-lap001
Assistant-Session: f2bff2d5-e9b2-4338-92ca-10282a927006

api/services/forge_projection.py

@@ -732,7 +732,13 @@ async def reset_repository_projection(
             # which is then deliberately un-retired below.
             matched[key] = row
             continue
-        if row.projection_retired_at is not None:
+        if row.projection_retired_at is not None or RETIRED_SLUG_MARK in (row.slug or ""):
+            # A stamped slug is itself evidence of a retirement, so a row
+            # carrying the mark with a cleared flag is a contradiction to
+            # repair rather than a live record — six rows reached that state
+            # before the resurrection was fixed, and nothing else can see them:
+            # they path-match their own file and report `noop` forever.
+            #
             # Past this point only the heuristics remain, and a retired row must
             # not be matched by those. Retirement is a
             # decision, and re-deriving the same file must not silently undo it.