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_test.go

@@ -379,7 +379,7 @@ func TestIsNotFoundError(t *testing.T) {
 	}{
 		{"nil error", nil, false},
 		{"HTTP 404", errors.New("HTTP 404: not found"), true},
-		{"not found text", errors.New("path not found"), true},
+		{"not found text", errors.New("path not found"), false},
 		{"server error", errors.New("server error"), false},
 		{"HTTP 500", errors.New("HTTP 500: internal error"), false},
 	}