add a check if app_name is wrong in rxconfig

[Lendemor]

No description provided.

[greptile-apps]

PR Summary

Added validation for app folder structure to ensure it matches the app_name specified in rxconfig.py. This helps catch configuration mismatches early.

• Added _check_app_folder_structure() in reflex/utils/prerequisites.py to validate app folder and main file existence
• Function checks if app folder exists at <cwd>/<app_name> and main file at <app_name>/<app_name>.py
• Validation is skipped if custom app_module_import is specified in config
• Raises clear error messages if folder structure doesn't match config
• Integrated check into get_app() flow after _check_app_name()

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[codspeed-hq]

CodSpeed Performance Report

Merging #5410 will not alter performance

_{Comparing lendemor/app_name_failsafe (5dc0346) with main (9e5a410)}

Summary

✅ 8 untouched benchmarks