v0.24.0 — Pre-testing observability: debug logging, diagnostic dump, startup self-test

- Add [DEBUG] logging across all modules (backup, storage, sync, selfupdate,
  monitor, notify, report, assets, setup) gated behind logging.level: "debug"
- Add /api/debug/dump endpoint returning full controller state JSON (debug only)
- Add startup self-test validating 9 subsystems (Docker, dirs, storage, hub,
  restic repos, metrics DB) with pass/warn/fail summary
- New packages: internal/selftest, internal/util
- Constructor/signature changes: debug bool params, logger params on
  RunHealthCheck and BuildReport, smart watchdog probe logging

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

controller/internal/backup/local_infra.go

@@ -24,12 +24,16 @@ type InfraMetadata struct {
 
 // WriteLocalInfraBackup writes the infra backup to .felhom-infra-backup/ on each drive.
 // Individual drive failures are logged but not returned — the function is best-effort.
-func WriteLocalInfraBackup(backupJSON []byte, customerID, controllerVersion, timestamp string, drives []string, logger *log.Logger) {
+func WriteLocalInfraBackup(backupJSON []byte, customerID, controllerVersion, timestamp string, drives []string, logger *log.Logger, debug bool) {
 	if len(drives) == 0 {
 		logger.Printf("[DEBUG] No drives configured for local infra backup")
 		return
 	}
 
+	if debug {
+		logger.Printf("[DEBUG] WriteLocalInfraBackup: payload size=%d bytes, %d target drive(s): %v", len(backupJSON), len(drives), drives)
+	}
+
 	// Compute checksum of backup data
 	hash := sha256.Sum256(backupJSON)
 	checksum := hex.EncodeToString(hash[:])
@@ -51,10 +55,16 @@ func WriteLocalInfraBackup(backupJSON []byte, customerID, controllerVersion, tim
 	written := 0
 	for _, drive := range drives {
 		dir := InfraBackupDir(drive)
+		if debug {
+			logger.Printf("[DEBUG] WriteLocalInfraBackup: writing to drive=%s, dir=%s", drive, dir)
+		}
 		if err := writeInfraToDir(dir, backupJSON, metaJSON); err != nil {
 			logger.Printf("[WARN] Local infra backup: failed to write to %s: %v", drive, err)
 			continue
 		}
+		if debug {
+			logger.Printf("[DEBUG] WriteLocalInfraBackup: write OK to %s", drive)
+		}
 		written++
 	}