feat: add registry repair framework

- add shared registry validation service
- add transaction-safe repair CLI
- refactor doctor to use validator
- improve restore integrity checks
- add registry repair integration tests
- strengthen global slug consistency

Cargo.lock

@@ -345,7 +345,7 @@ checksum = "1e748733b7cbc798e1434b6ac524f0c1ff2ab456fe201501e6497c8417a4fc33"
 
 [[package]]
 name = "bzod"
-version = "0.5.1"
+version = "0.5.2"
 dependencies = [
  "argon2",
  "askama",