WP-0016 finished: interactive registry maintain with llm-connect automation

Closes the registry maintenance loop from inside each domain repo:
interactive prompting for judgment calls, full automation for safe and
high-confidence changes, both backed by the llm-connect HTTP bridge.

- New modules: maintain.py, maintain_llm.py, patches.py, interactive.py
- Schema: schemas/registry-patch.schema.json
- CLI: reuse-surface maintain; establish --scaffold --hook
- Sibling templates: Makefile fragment, pre-commit hook
- Deterministic signal collectors extended; validate cwd auto-detect
- Docs, gap priority 28, SCOPE update
- Tests: test_maintain.py, test_interactive.py (59 pytest total)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

schemas/registry-patch.schema.json

@@ -0,0 +1,83 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://reuse-surface.local/schemas/registry-patch.schema.json",
+  "title": "RegistryMaintainPatchSet",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["patches"],
+  "properties": {
+    "patches": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "additionalProperties": false,
+        "required": ["capability_id", "kind", "confidence", "rationale"],
+        "properties": {
+          "capability_id": {
+            "type": "string",
+            "pattern": "^capability\\.[a-z0-9]+(\\.[a-z0-9-]+)+$"
+          },
+          "kind": {
+            "type": "string",
+            "enum": [
+              "vector_sync",
+              "evidence_append",
+              "artifact_append",
+              "maturity_promote",
+              "consumer_feedback",
+              "relation_add",
+              "index_row_add",
+              "index_updated_bump"
+            ]
+          },
+          "confidence": {
+            "type": "string",
+            "enum": ["low", "medium", "high"]
+          },
+          "rationale": {
+            "type": "string",
+            "minLength": 1
+          },
+          "field_path": {
+            "type": "string"
+          },
+          "value": {},
+          "append": {
+            "type": "string"
+          },
+          "dimension": {
+            "type": "string",
+            "enum": ["discovery", "availability", "completeness", "reliability"]
+          },
+          "from_level": {
+            "type": "string"
+          },
+          "to_level": {
+            "type": "string"
+          },
+          "promotion_history_entry": {
+            "type": "object",
+            "additionalProperties": true
+          },
+          "index_row": {
+            "type": "object",
+            "additionalProperties": true
+          },
+          "evidence_citations": {
+            "type": "array",
+            "items": {
+              "type": "string",
+              "minLength": 1
+            }
+          }
+        }
+      }
+    },
+    "notes": {
+      "type": "array",
+      "items": {
+        "type": "string"
+      }
+    }
+  }
+}