Handle 429 rate-limit responses before empty-body fallback

[simonachmueller]

Summary

• add a dedicated TadoRateLimitException for exhausted API quota responses
• handle HTTP 429 in Http.request() before the empty-body fallback that currently returns {}
• include RateLimit-Policy, RateLimit, and Retry-After details in the raised exception message
• add a regression test for 429 + empty body so /api/v2/me throttling no longer cascades into KeyError('homes')

Why

When Tado rate limits /api/v2/me, responses can be 429 with an empty body. The previous flow returned {} for empty responses and later attempted response[\"homes\"], causing a misleading KeyError.

This PR makes rate-limit exhaustion explicit and actionable.

Closes #294.

Test

• uv run --with pytest --with responses --with pytest-socket --with typing-extensions --with pydantic python -m pytest tests/test_http.py

[simonachmueller]

@wmalgadey any chance to take a look?

[codecov]

Codecov Report

❌ Patch coverage is 70.58824% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.16%. Comparing base (8b86e5c) to head (2d7d8cd).
⚠️ Report is 2 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
PyTado/http.py	68.75%	1 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #295      +/-   ##
==========================================
- Coverage   76.22%   76.16%   -0.06%     
==========================================
  Files          37       37              
  Lines        2191     2207      +16     
  Branches      129      134       +5     
==========================================
+ Hits         1670     1681      +11     
- Misses        484      485       +1     
- Partials       37       41       +4     

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