feat: add AI Bridge request logs model filter (#22230)

This pull-request implements a simple filtering logic so that we're able
to pick which model the user actually used when logs were sent to AI
Bridge.

- Add `GET /aibridge/models` API endpoint that returns distinct model
names from AI Bridge interceptions, with pagination and search support
- New `ListAIBridgeModels` SQL query using case-sensitive prefix
matching (`LIKE model || '%'`) to allow B-tree index usage
- Hand-written `ListAuthorizedAIBridgeModels` in `modelqueries.go` for
RBAC authorization filter injection
- `AIBridgeModels` search query parser in searchquery/search.go
(defaults bare terms to the `model` field)
- dbauthz wrappers, dbmetrics, and dbmock implementations for the new
query

<img width="292" height="185" alt="image"
src="https://github.com/user-attachments/assets/134771df-2d26-4c54-acc4-27f58128b351"
/>

coderd/apidoc/docs.go

@@ -135,6 +135,34 @@ const docTemplate = `{
                 }
             }
         },
+        "/aibridge/models": {
+            "get": {
+                "security": [
+                    {
+                        "CoderSessionToken": []
+                    }
+                ],
+                "produces": [
+                    "application/json"
+                ],
+                "tags": [
+                    "AI Bridge"
+                ],
+                "summary": "List AI Bridge models",
+                "operationId": "list-ai-bridge-models",
+                "responses": {
+                    "200": {
+                        "description": "OK",
+                        "schema": {
+                            "type": "array",
+                            "items": {
+                                "type": "string"
+                            }
+                        }
+                    }
+                }
+            }
+        },
         "/appearance": {
             "get": {
                 "security": [

coderd/apidoc/swagger.json

@@ -112,6 +112,30 @@
 				}
 			}
 		},
+		"/aibridge/models": {
+			"get": {
+				"security": [
+					{
+						"CoderSessionToken": []
+					}
+				],
+				"produces": ["application/json"],
+				"tags": ["AI Bridge"],
+				"summary": "List AI Bridge models",
+				"operationId": "list-ai-bridge-models",
+				"responses": {
+					"200": {
+						"description": "OK",
+						"schema": {
+							"type": "array",
+							"items": {
+								"type": "string"
+							}
+						}
+					}
+				}
+			}
+		},
 		"/appearance": {
 			"get": {
 				"security": [