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/database/queries.sql.go

@@ -928,6 +928,60 @@ func (q *sqlQuerier) ListAIBridgeInterceptionsTelemetrySummaries(ctx context.Con
 	return items, nil
 }
 
+const listAIBridgeModels = `-- name: ListAIBridgeModels :many
+SELECT
+	model
+FROM
+	aibridge_interceptions
+WHERE
+	-- Remove inflight interceptions (ones which lack an ended_at value).
+	aibridge_interceptions.ended_at IS NOT NULL
+	-- Filter model
+	AND CASE
+		WHEN $1::text != '' THEN aibridge_interceptions.model LIKE $1::text || '%'
+		ELSE true
+	END
+	-- We use an ` + "`" + `@authorize_filter` + "`" + ` as we are attempting to list models that are relevant
+	-- to the user and what they are allowed to see.
+	-- Authorize Filter clause will be injected below in ListAIBridgeModelsAuthorized
+	-- @authorize_filter
+GROUP BY
+	model
+ORDER BY
+	model ASC
+LIMIT COALESCE(NULLIF($3::integer, 0), 100)
+OFFSET $2
+`
+
+type ListAIBridgeModelsParams struct {
+	Model  string `db:"model" json:"model"`
+	Offset int32  `db:"offset_" json:"offset_"`
+	Limit  int32  `db:"limit_" json:"limit_"`
+}
+
+func (q *sqlQuerier) ListAIBridgeModels(ctx context.Context, arg ListAIBridgeModelsParams) ([]string, error) {
+	rows, err := q.db.QueryContext(ctx, listAIBridgeModels, arg.Model, arg.Offset, arg.Limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []string
+	for rows.Next() {
+		var model string
+		if err := rows.Scan(&model); err != nil {
+			return nil, err
+		}
+		items = append(items, model)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const listAIBridgeTokenUsagesByInterceptionIDs = `-- name: ListAIBridgeTokenUsagesByInterceptionIDs :many
 SELECT
 	id, interception_id, provider_response_id, input_tokens, output_tokens, metadata, created_at