fix: batch pskr calibration upsert into 1,000-row chunks to avoid Postgres 65,535 param limit

lib/microwaveprop/pskr/calibration_sampler.ex

@@ -267,11 +267,19 @@ defmodule Microwaveprop.Pskr.CalibrationSampler do
 
   # ── Upsert ──────────────────────────────────────────────────────
 
+  # Each sample has ~20 fields. PostgreSQL's parameter limit is 65,535,
+  # so a single insert_all with > ~3,200 rows will fail. Batch at 1,000
+  # to stay well under the limit even at peak hours.
+  @upsert_batch_size 1_000
+
   defp upsert([]), do: 0
 
   defp upsert(samples) do
+    samples
+    |> Enum.chunk_every(@upsert_batch_size)
+    |> Enum.reduce(0, fn batch, total ->
       {count, _} =
-      Repo.insert_all(CalibrationSample, samples,
+        Repo.insert_all(CalibrationSample, batch,
           on_conflict:
             from(c in CalibrationSample,
               update: [
@@ -295,7 +303,8 @@ defmodule Microwaveprop.Pskr.CalibrationSampler do
           conflict_target: [:hour_utc, :band, :midpoint_lat, :midpoint_lon]
         )
 
-    count
+      total + count
+    end)
   end
 
   defp align_to_hour(%DateTime{} = dt) do