feat: comprehensive INFO/WARN/ERROR logging across all controller modules

Add structured operational logging at INFO, WARN, and ERROR levels to
every controller module. Standardize custom prefixes ([GEO], [SCHED],
[SYNC]) to use [INFO/WARN/ERROR] [module] format. Fix misleveled logs
(WARN->ERROR for data loss scenarios, WARN->INFO for routine operations).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/assets/syncer.go

@@ -218,7 +218,7 @@ func (s *Syncer) setError(err error) {
 		TotalBytes: s.status.TotalBytes,
 	}
 	s.mu.Unlock()
-	s.logger.Printf("[WARN] Asset sync failed: %v", err)
+	s.logger.Printf("[ERROR] [assets] Asset sync failed: %v", err)
 }
 
 func (s *Syncer) fetchManifest(ctx context.Context) (*HubManifest, error) {
@@ -316,14 +316,18 @@ func (s *Syncer) downloadFile(ctx context.Context, filename string) error {
 func (s *Syncer) saveLocalManifest(manifest *HubManifest) {
 	data, err := json.MarshalIndent(manifest, "", "  ")
 	if err != nil {
+		s.logger.Printf("[ERROR] [assets] Failed to save local manifest: %v", err)
 		return
 	}
 	path := filepath.Join(s.assetsDir, "manifest.json")
 	tmp := path + ".tmp"
 	if err := os.WriteFile(tmp, data, 0644); err != nil {
+		s.logger.Printf("[ERROR] [assets] Failed to save local manifest: %v", err)
 		return
 	}
-	os.Rename(tmp, path)
+	if err := os.Rename(tmp, path); err != nil {
+		s.logger.Printf("[ERROR] [assets] Failed to save local manifest: %v", err)
+	}
 }
 
 func fileSHA256(path string) (string, error) {