fix(weather): analyze_all skip_recent check reads both analyze timestamps

pg_stat_user_tables tracks two timestamps — `last_autoanalyze`
is only bumped by the autovacuum daemon, while `last_analyze` is
bumped by manual ANALYZE statements (including the ones our Task
issues). The previous query only filtered on `last_autoanalyze`,
so on a re-run within the skip_recent window every manually-
analyzed table came back for another ANALYZE pass.

Uses `GREATEST(last_analyze, last_autoanalyze)` so fresh manual
analyses count as recent.

lib/microwaveprop/weather.ex

@@ -434,12 +434,18 @@ defmodule Microwaveprop.Weather do
   def analyze_all(opts \\ []) do
     skip_recent = Keyword.get(opts, :skip_recent_seconds, 6 * 3600)
 
+    # `last_autoanalyze` is only set by the autovacuum daemon;
+    # `last_analyze` is set by manual ANALYZE (including our Task
+    # below). Take the newer of the two — otherwise a re-run within
+    # `skip_recent` would re-analyze everything we just did.
     q = """
     SELECT relname
     FROM pg_stat_user_tables
     WHERE schemaname = 'public'
-      AND (last_autoanalyze IS NULL
-           OR last_autoanalyze < now() - ($1 || ' seconds')::interval)
+      AND COALESCE(
+        GREATEST(last_analyze, last_autoanalyze),
+        'epoch'::timestamptz
+      ) < now() - ($1 || ' seconds')::interval
     ORDER BY n_live_tup ASC
     """