chore: add offset-based pagination support to aibridge list endpoint (#20393)

Necessary for the frontend to be able to paginate easily. Cursor
pagination is good for fetching all events, but doesn't play very well
when a pagination component gets involved.

Adds support for `?offset=x` to the existing endpoint. The cursor-based
pagination (`?after_id=x`) is still supported. The two pagination modes
are mutually exclusive, and are documented as such. If both are
supplied, the request will be rejected.

Also adds a `total` property to the response that contains the full
count of items matching the filter. We already have indices in place so
I don't think this will impact performance (or we can revisit it before
GA).

coderd/database/queries/aibridge.sql

@@ -75,6 +75,40 @@ ORDER BY
 	created_at ASC,
 	id ASC;
 
+-- name: CountAIBridgeInterceptions :one
+SELECT
+	COUNT(*)
+FROM
+	aibridge_interceptions
+WHERE
+	-- Filter by time frame
+	CASE
+		WHEN @started_after::timestamptz != '0001-01-01 00:00:00+00'::timestamptz THEN aibridge_interceptions.started_at >= @started_after::timestamptz
+		ELSE true
+	END
+	AND CASE
+		WHEN @started_before::timestamptz != '0001-01-01 00:00:00+00'::timestamptz THEN aibridge_interceptions.started_at <= @started_before::timestamptz
+		ELSE true
+	END
+	-- Filter initiator_id
+	AND CASE
+		WHEN @initiator_id::uuid != '00000000-0000-0000-0000-000000000000'::uuid THEN aibridge_interceptions.initiator_id = @initiator_id::uuid
+		ELSE true
+	END
+	-- Filter provider
+	AND CASE
+		WHEN @provider::text != '' THEN aibridge_interceptions.provider = @provider::text
+		ELSE true
+	END
+	-- Filter model
+	AND CASE
+		WHEN @model::text != '' THEN aibridge_interceptions.model = @model::text
+		ELSE true
+	END
+	-- Authorize Filter clause will be injected below in ListAuthorizedAIBridgeInterceptions
+	-- @authorize_filter
+;
+
 -- name: ListAIBridgeInterceptions :many
 SELECT
 	*
@@ -127,6 +161,7 @@ ORDER BY
 	aibridge_interceptions.started_at DESC,
 	aibridge_interceptions.id DESC
 LIMIT COALESCE(NULLIF(@limit_::integer, 0), 100)
+OFFSET @offset_
 ;
 
 -- name: ListAIBridgeTokenUsagesByInterceptionIDs :many