feat(agent): add online verification and governing-answer citations

Claim-bound online verification observations with URL provenance, exact
answer-basis references for citation-free governing-rule answers, and an
explicit operator identity handoff before source transfer. Bounds resumed
work by learning unit and refreshes pack manifest/contracts.

contracts/schemas/ProposalRevision.schema.json

@@ -32,6 +32,15 @@
           "title": "Evidence Type",
           "type": "string"
         },
+        "online_evidence": {
+          "default": [],
+          "items": {
+            "$ref": "#/$defs/OnlineEvidence"
+          },
+          "maxItems": 20,
+          "title": "Online Evidence",
+          "type": "array"
+        },
         "schema_version": {
           "const": 1,
           "default": 1,
@@ -633,6 +642,54 @@
       "title": "NodeType",
       "type": "string"
     },
+    "OnlineEvidence": {
+      "additionalProperties": false,
+      "description": "A short online excerpt with its relationship to a claim and verification URL.",
+      "properties": {
+        "context": {
+          "maxLength": 4000,
+          "minLength": 1,
+          "title": "Context",
+          "type": "string"
+        },
+        "relation": {
+          "enum": [
+            "supports",
+            "contradicts",
+            "context",
+            "inconclusive"
+          ],
+          "title": "Relation",
+          "type": "string"
+        },
+        "schema_version": {
+          "const": 1,
+          "default": 1,
+          "title": "Schema Version",
+          "type": "integer"
+        },
+        "text": {
+          "maxLength": 8000,
+          "minLength": 1,
+          "title": "Text",
+          "type": "string"
+        },
+        "url": {
+          "maxLength": 4000,
+          "minLength": 1,
+          "title": "Url",
+          "type": "string"
+        }
+      },
+      "required": [
+        "url",
+        "text",
+        "relation",
+        "context"
+      ],
+      "title": "OnlineEvidence",
+      "type": "object"
+    },
     "ProposalOperation": {
       "additionalProperties": false,
       "properties": {
@@ -662,6 +719,7 @@
           "enum": [
             "register_source",
             "upsert_node",
+            "update_node",
             "add_edge",
             "flag_stale"
           ],