merge(plane): manifest schemas and validation (task 1)

Audit registry conflict resolved: plane, plane.budget and plane.manifests rows kept; manifest regenerated from the merged tree.

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

benchmarks/measurements/2026-09-08-module-audit.json

@@ -1,7 +1,7 @@
 {
-  "modules": 120,
+  "modules": 121,
   "counts": {
-    "load_bearing": 111,
+    "load_bearing": 112,
     "standalone_capability": 9
   },
   "orphaned": [],
@@ -661,6 +661,12 @@
       "reason": "ai-service-plane Req 2.3/2.4: metered chat client with usd and calls ceilings; task integration in tasks 3, 6",
       "importers": []
     },
+    {
+      "module": "plane.manifests",
+      "classification": "load_bearing",
+      "reason": "ai-service-plane Req 1.1-1.4: ax-shaped Task/Workspace/Model and the Run kind, validated before anything runs",
+      "importers": []
+    },
     {
       "module": "policy",
       "classification": "load_bearing",