feat: online verification, node removals, and knowledge browser

Adds claim-bound online evidence records and citation verification scripts,
node removal transport/adapter, retrieval benchmark and owner-review tooling,
GraphCanvas/SourceDetail knowledge browser UI, and the ingest handoff helper.
Bumps the agents/gewu pack to the online-verification branch.

schema/v1/records/KnowledgeNode.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,
@@ -282,6 +291,54 @@
       "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"
+    },
     "ReviewState": {
       "enum": [
         "draft",