Split ENABLE_LEGACY_PROVIDER_JOBS into independent FTP/HARMONIE flags

Real LVGMC FTP credentials arrived today; real DMI HARMONIE
credentials haven't. The combined flag would have enabled both the
moment FTP's were ready, crash-looping the app on HARMONIE's still-
placeholder values via parMapN — caught this before it happened
(the Grib job was ~15 min from its first scheduled run). Split into
ENABLE_LVGMC_FTP_JOBS and ENABLE_HARMONIE_JOBS so each provider can
be enabled independently as its own credentials become real.

src/main/scala/Main.scala

@@ -68,12 +68,26 @@ object Main extends IOApp {
         else
           (fetchOpenDataStationsTask, cleanupTask).parMapN((_, _) => ())
 
-      legacyProviderTasks =
-        if (sys.env.get("ENABLE_LEGACY_PROVIDER_JOBS").exists(_.equalsIgnoreCase("true")))
-          (fetchStationsTask, fetchGribTask).parMapN((_, _) => ())
+      // FTP (LVGMC) and HARMONIE (DMI) are gated independently: each only
+      // throws once its own real credentials arrive, and they arrive on
+      // different timelines (FTP creds obtained 2026-08-23; HARMONIE still
+      // pending). A single combined flag would enable both together the
+      // moment either one's credentials were ready, crash-looping the app
+      // on whichever provider still had placeholders.
+      ftpStationTask =
+        if (sys.env.get("ENABLE_LVGMC_FTP_JOBS").exists(_.equalsIgnoreCase("true")))
+          fetchStationsTask
         else
           IO.never[Unit]
 
+      harmonieTask =
+        if (sys.env.get("ENABLE_HARMONIE_JOBS").exists(_.equalsIgnoreCase("true")))
+          fetchGribTask
+        else
+          IO.never[Unit]
+
+      legacyProviderTasks = (ftpStationTask, harmonieTask).parMapN((_, _) => ())
+
       scheduledTasks = (safeTasks, legacyProviderTasks).parMapN((_, _) => ())
 
       exitCode <- (serverTask, scheduledTasks).parMapN((_, _) => ExitCode.Success)