add error logging to LoadMetadata, fix deploy sed command

- Log YAML parse errors in LoadMetadata instead of silently swallowing
- Add debug log for successful metadata loads (tagline, useCases, optConfig counts)
- Fix CLAUDE.md deploy command: use sudo, target only image: line in sed

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

controller/internal/stacks/metadata.go

@@ -1,6 +1,7 @@
 package stacks
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
@@ -92,13 +93,16 @@ func LoadMetadata(stackDir string) Metadata {
 	}
 
 	if err := yaml.Unmarshal(data, &meta); err != nil {
-		// Parse error — still return defaults
+		fmt.Fprintf(os.Stderr, "[ERROR] Failed to parse .felhom.yml in %s: %v\n", stackDir, err)
 		dirName := filepath.Base(stackDir)
 		meta.DisplayName = toTitleCase(strings.ReplaceAll(dirName, "-", " "))
 		meta.Slug = dirName
 		return meta
 	}
 
+	fmt.Fprintf(os.Stderr, "[DEBUG] Loaded metadata for %s: tagline=%q, useCases=%d, optConfig=%d\n",
+		filepath.Base(stackDir), meta.AppInfo.Tagline, len(meta.AppInfo.UseCases), len(meta.OptionalConfig))
+
 	// Fill in defaults for missing fields
 	dirName := filepath.Base(stackDir)
 	if meta.Slug == "" {