feat: warnings en indexer para file_path inexistentes en disco

Valida post-insert que file_path y test_file_path de funciones y tipos apunten a archivos reales. Reporta warnings sin bloquear el indexado.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cmd/fn/main.go

@@ -127,6 +127,9 @@ func cmdIndex() {
 	for _, e := range result.ValidationErrors {
 		fmt.Fprintf(os.Stderr, "  INVALID: %s\n", e)
 	}
+	for _, w := range result.Warnings {
+		fmt.Fprintf(os.Stderr, "  WARN: %s\n", w)
+	}
 	for _, e := range result.Errors {
 		fmt.Fprintf(os.Stderr, "  ERROR: %s\n", e)
 	}

registry/indexer.go

@@ -15,6 +15,7 @@ type IndexResult struct {
 	Apps             int
 	Analysis         int
 	ValidationErrors []string
+	Warnings         []string
 	Errors           []string
 }
 
@@ -202,6 +203,30 @@ func Index(db *DB, root string) (*IndexResult, error) {
 		result.Analysis++
 	}
 
+	// Post-insert: warn about file_path entries that don't exist on disk
+	for _, f := range functions {
+		if f.FilePath != "" {
+			abs := filepath.Join(root, f.FilePath)
+			if _, err := os.Stat(abs); err != nil {
+				result.Warnings = append(result.Warnings, fmt.Sprintf("%s: file_path %q not found", f.ID, f.FilePath))
+			}
+		}
+		if f.TestFilePath != "" {
+			abs := filepath.Join(root, f.TestFilePath)
+			if _, err := os.Stat(abs); err != nil {
+				result.Warnings = append(result.Warnings, fmt.Sprintf("%s: test_file_path %q not found", f.ID, f.TestFilePath))
+			}
+		}
+	}
+	for _, t := range types {
+		if t.FilePath != "" {
+			abs := filepath.Join(root, t.FilePath)
+			if _, err := os.Stat(abs); err != nil {
+				result.Warnings = append(result.Warnings, fmt.Sprintf("%s: file_path %q not found", t.ID, t.FilePath))
+			}
+		}
+	}
+
 	return result, nil
 }