fix(query): route GUID group-by to eval path, unblocks (select {by: guid})

(select {from: t by: OrderId}) on 10M rows / 1M distinct GUIDs
hung for minutes (effectively forever) and could not be Ctrl-C'd.

Two compounding bugs in the DAG no-agg no-nonagg branch at
query.c:1700-1708:

  * The first-occurrence scan is O(N × n_groups) — 10M × 1M = 10
    trillion comparisons, and there is no ray_interrupted() check
    inside the inner loop.
  * It reads the key column through ray_read_sym which truncates
    RAY_GUID to the first 8 bytes, so the comparison is not even
    semantically correct for wide keys.

Route RAY_GUID group-by to the eval-level path unconditionally
(previously gated on any_nonagg). ray_group_fn already has a
proper open-addressed 16-byte hash table plus the interrupt /
progress hooks added in the previous commits, so the query now
finishes in ~1.3 s (down from "hang") on the 10M row benchmark.

The O(N × n_groups) integer path is still latent for non-GUID
wide-ish workloads and should get the same hash-table rewrite,
but that is out of scope here — GUID was the reported hang.

Author: singaraiona

src/ops/query.c

@@ -1028,7 +1028,16 @@ ray_t* ray_select_fn(ray_t** args, int64_t n) {
                 if (RAY_IS_PARTED(kct)) kct = (int8_t)RAY_PARTED_BASETYPE(kct);
                 if (kct == RAY_LIST || kct == RAY_STR)
                     use_eval_group = 1;
-                else if (kct == RAY_GUID && any_nonagg)
+                else if (kct == RAY_GUID)
+                    /* RAY_GUID keys always route to the eval-level
+                     * ray_group_fn path: (a) the DAG first-occurrence
+                     * scanner below truncates wide keys to 8 bytes
+                     * via ray_read_sym and is buggy for GUIDs, and
+                     * (b) its O(N × n_groups) nested fallback was
+                     * hanging for minutes on 10M-row tables with
+                     * ~1M distinct groups. ray_group_fn has a proper
+                     * open-addressed 16-byte HT plus interrupt
+                     * checkpoints. */
                     use_eval_group = 1;
             }
         }