Fix missing precipitation columns and backfill weather data

Add idempotent migration to ensure precip_1h_in and wx_codes columns
exist, then reset weather_queued flag and clear stale observations
so the cron re-fetches with precipitation data included.

priv/repo/migrations/20260330182625_ensure_precipitation_columns.exs

@@ -0,0 +1,32 @@
+defmodule Microwaveprop.Repo.Migrations.EnsurePrecipitationColumns do
+  use Ecto.Migration
+
+  def up do
+    execute """
+    DO $$
+    BEGIN
+      IF NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_name = 'surface_observations' AND column_name = 'precip_1h_in'
+      ) THEN
+        ALTER TABLE surface_observations ADD COLUMN precip_1h_in double precision;
+      END IF;
+
+      IF NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_name = 'surface_observations' AND column_name = 'wx_codes'
+      ) THEN
+        ALTER TABLE surface_observations ADD COLUMN wx_codes character varying(255);
+      END IF;
+    END
+    $$;
+    """
+  end
+
+  def down do
+    alter table(:surface_observations) do
+      remove :precip_1h_in
+      remove :wx_codes
+    end
+  end
+end

priv/repo/migrations/20260330182652_backfill_surface_observations_with_precipitation.exs

@@ -0,0 +1,17 @@
+defmodule Microwaveprop.Repo.Migrations.BackfillSurfaceObservationsWithPrecipitation do
+  use Ecto.Migration
+
+  def up do
+    # Delete surface observations that were fetched without precipitation data
+    # so the weather cron re-fetches them with the new p01i/wxcodes fields
+    execute "DELETE FROM surface_observations WHERE precip_1h_in IS NULL AND wx_codes IS NULL"
+
+    # Reset the weather_queued flag so QSOs are re-enqueued for weather fetching
+    execute "UPDATE qsos SET weather_queued = false"
+  end
+
+  def down do
+    # Cannot restore deleted observations; no-op
+    :ok
+  end
+end