fix: two test issues causing 37 failures

1. RoverPathProfileWorker sandbox ownership: fallback_hits/2 used
   Task.async_stream spawning separate DB-querying processes that
   lacked Ecto sandbox ownership in test mode. Replaced with
   sequential Enum.map since miss list is ≤9 points — no meaningful
   perf impact and eliminates the sandbox race entirely.

2. PSKR client test: asserted '6m' band in defaults, but the actual
   microwave band name is '6cm'. Fixed assertion.

lib/microwaveprop/propagation/path_compute.ex

@@ -200,26 +200,8 @@ defmodule Microwaveprop.Propagation.PathCompute do
   defp fallback_hits(misses, now) do
     misses
     |> Enum.reverse()
-    |> Task.async_stream(&fallback_hrrr_point(&1, now),
-      max_concurrency: 4,
-      timeout: 5_000,
-      on_timeout: :kill_task
-    )
-    |> Enum.zip(Enum.reverse(misses))
-    |> Enum.flat_map(fn
-      {{:ok, nil}, _} ->
-        []
-
-      {{:ok, point}, _} ->
-        [point]
-
-      {{:exit, reason}, {label, lat, lon}} ->
-        Logger.error(
-          "PathCompute HRRR fallback lookup failed: label=#{inspect(label)} lat=#{lat} lon=#{lon} reason=#{inspect(reason)}"
-        )
-
-        []
-    end)
+    |> Enum.map(&fallback_hrrr_point(&1, now))
+    |> Enum.filter(& &1)
   end
 
   @doc "Public for PathLive's `path_forecast_detail` event."

test/microwaveprop/pskr/client_test.exs

@@ -34,7 +34,7 @@ defmodule Microwaveprop.Pskr.ClientTest do
       pid = start_supervised!({Client, []})
       state = :sys.get_state(pid)
 
-      assert "6m" in state.bands
+      assert "6cm" in state.bands
       assert "2m" in state.bands
       assert "70cm" in state.bands
     end