- Split `p3` module into `p3_pardakht_novin` and `p3_sepehr` sub-modules
- Create `pardakht_novin_app` module with dedicated WebView and Hilt configuration
- Rename P3 services, printers, and models to be vendor-specific (e.g., `P3PardakhtNovinService`)
- Add `p3_pardakht_novin` and `p3_sepehr` product flavors to `tis_app` and `stage_app`
- Update project settings and build configurations to include the new modular structure
- Implement Sepehr-specific POS and Printer services in the new module
- Refactor `PaymentResultEntity` to include a nested `PaymentResultDataEntity` and companion factory methods for success and failure.
- Update `PaymentResultStatus` enum members from `OK`/`ERROR` to `SUCCESS`/`FAILURE`.
- Modify `PspService` and its implementations (`P3`, `PS4`, `Stage`) to return a non-nullable `PaymentResultEntity`.
- Enhance `PspWebView` with improved instance lifecycle management, `rememberUpdatedState` for callbacks, and new `onWebViewReady` and `onPageFinished` hooks.
- Optimize `PspWebView` to prevent redundant `loadUrl` calls during recomposition.
- Add `README.md` and `AGENT.md` to provide project architecture overviews and hardware-specific development guidelines.
- Update `TisWebViewScreen` and `StageWebViewScreen` to handle the refactored result models and utilize new WebView callbacks.