fix: address PR #62 review findings

- Remove duplicate flag.Parse() call
- Fix nil map panic in LoadRemotePersonas error path by assigning
  empty map when LoadRemotePersonas returns an error
- Tighten isNotFoundError to only check HTTP 404 (remove broad
  'not found' substring check to avoid false positives)
- Clean up personaErr variable scope using narrower-scoped err variables
- Add proper doc comment to LoadRemotePersonasFromPath (Go convention)
- Add file count cap (50 files) in LoadRemotePersonasFromPath to
  prevent resource exhaustion from repos with thousands of small files
- Update test expectation for tightened isNotFoundError

review/remote_persona.go

@@ -40,7 +40,9 @@ func LoadRemotePersonas(ctx context.Context, fetcher PersonaFetcher, owner, repo
 	return LoadRemotePersonasFromPath(ctx, fetcher, owner, repo, DefaultPersonasPath)
 }
 
-// LoadRemotePersonasFromPath is like LoadRemotePersonas but allows specifying a custom path.
+// LoadRemotePersonasFromPath loads personas from a custom path in a remote repository.
+// It behaves the same as LoadRemotePersonas but allows specifying a path other than
+// the default .review-bot/personas directory.
 func LoadRemotePersonasFromPath(ctx context.Context, fetcher PersonaFetcher, owner, repo, path string) (map[string]*Persona, error) {
 	entries, err := fetcher.ListContents(ctx, owner, repo, path)
 	if err != nil {
@@ -52,8 +54,17 @@ func LoadRemotePersonasFromPath(ctx context.Context, fetcher PersonaFetcher, own
 		return nil, fmt.Errorf("list remote personas: %w", err)
 	}
 
+	// Cap the number of files to process to prevent resource exhaustion
+	// from repos with thousands of small files.
+	const maxPersonaFiles = 50
+
 	result := make(map[string]*Persona)
+	processed := 0
 	for _, entry := range entries {
+		if processed >= maxPersonaFiles {
+			slog.Warn("persona file limit reached", "limit", maxPersonaFiles, "repo", fmt.Sprintf("%s/%s", owner, repo))
+			break
+		}
 		if ctx.Err() != nil {
 			return nil, ctx.Err()
 		}
@@ -85,6 +96,7 @@ func LoadRemotePersonasFromPath(ctx context.Context, fetcher PersonaFetcher, own
 		}
 
 		result[persona.Name] = persona
+		processed++
 		slog.Debug("loaded remote persona", "name", persona.Name, "file", entry.Path)
 	}
 
@@ -148,5 +160,5 @@ func isNotFoundError(err error) bool {
 		return false
 	}
 	errStr := err.Error()
-	return strings.Contains(errStr, "HTTP 404") || strings.Contains(errStr, "not found")
+	return strings.Contains(errStr, "HTTP 404")
 }