feat(#2591): add GET /api/build-log/<node_id> {,/raw} query endpoints

The raw-graph wire drops the inline build_log_id; the client fetches a
node's captured output on demand. Two handlers resolve node id -> log-row
id (JobQueue::build_log_id_of, now keyed by the wire u64) then delegate to
the existing get_full / raw handlers: /api/build-log/<node_id> serves the
BuildLogFull JSON ({stdout, stderr} + header), /raw serves text/plain.
404 when the node has no linked log.

hive-c0re/src/dashboard/mod.rs

@@ -100,6 +100,14 @@ pub async fn serve(
         )
         .route("/api/audit-log", get(misc_api::api_audit_log))
         .route("/api/build-logs", get(build_logs::get_build_logs_all))
+        .route(
+            "/api/build-log/{node_id}",
+            get(build_logs::get_build_log_for_node),
+        )
+        .route(
+            "/api/build-log/{node_id}/raw",
+            get(build_logs::get_build_log_raw_for_node),
+        )
         .route(
             "/api/build-logs/{agent}",
             get(build_logs::get_build_logs_agent),