Add read-only India iSMART support

[john-lazarus]

Adds a first pass at India iSMART support in a separate saic_ismart_client_ng.india module.

What is included:

• India TAP and gateway endpoints for mgindia.co.in
• phone number normalization and stable device id generation
• TAP login request/signature handling
• India gateway request signing headers
• AES-CBC response decrypt helper for encrypted gateway payloads
• vehicle list parsing
• read-only vehicle status request/response codec for TAP protocol 513
• status parsing for doors, windows, lock state, temperatures, fuel/range, odometer, CAN activity, aux battery voltage, handbrake, and similar basic fields

I have intentionally kept this read-only for now. Remote commands should probably come in a separate PR once the status/login path has had more testing.

Validation run locally:

• pytest tests/test_india_api.py -q
• pytest -q --disable-warnings
• ruff check src/saic_ismart_client_ng/india tests/test_india_api.py
• python -m compileall -q src/saic_ismart_client_ng/india tests/test_india_api.py
• git diff --check

All tests pass locally: 33 passed.

[yk1n9]

How do you install this to our home assistant ?

[nanomad]

@john-lazarus I appreciate the contribution, altough I'd like to mantain a compatible client API if possibile. Do you think that's feasible?

[john-lazarus]

Yes, I think that is feasible. India still needs a different transport internally because its login and status flow are different, but I can adapt it to expose the existing client API and return the existing schema types rather than introducing a parallel public model.

My inclination is to keep the India implementation behind the same method contract (vehicle_list(), get_vehicle_status(), and so on). Would you prefer that as a region-aware backend selected by SaicApi, or as a separate class implementing the same interface? Once I know which shape you prefer, I’ll rework the PR.