feat: track official versions and import resources

Persist official version-state, extend CAS/ResourceRepository import classification, and add offline catalog and failure regression fixtures.

Fixes #13

Fixes #12

Fixes #8

infrastructure/tests/golden/synthetic_phase2_import.json

@@ -2,6 +2,8 @@
   "imported": [
     {
       "bytes": 143,
+      "category": "asset_bundle",
+      "resource_type": "AssetBundle",
       "source_path": "synthetic/minimal.bundle",
       "unityfs": {
         "block_count": 1,
@@ -13,6 +15,9 @@
       }
     }
   ],
+  "category_counts": {
+    "asset_bundle": 1
+  },
   "resource_count": 1,
   "skipped": [
     "synthetic/catalog.json"