chore: regenerate models with parent-scoped naming and modernize tooling

[orest-tokovenko-block]

Splits the monolithic generated models file into individual modules, adds VCR cassette testing via pytest-recording to fix flakey CI runs, and replaces mypy with basedpyright for more modern type checking

VCR cassette testing

• Added pytest-recording with VCR_ENABLED env var toggle
• Recorded 59 cassettes in tests/cassettes/ for offline test replay
• CI auto-enables VCR with --record-mode=none --block-network
• Added just test-vcr, test-vcr-record, test-vcr-rewrite, and test-live commands

Codegen and tooling

• Split generated models from single __init__.py into individual files via module-split-mode = "single"
• Moved codegen flags from justfile into pyproject.toml; spec is now fetched via URL
• Replaced mypy with basedpyright (strict mode, gen_models excluded)
• Added pytest-timeout, pinned PyPI index to prevent proxy injection by my corporate machine's python config (it's a pain to fight it)

SDK

• Added timeout property and get_virtual_tag_processing_status() method
• Simplified _post/_put to always accept BaseModel