feat: remove retired lucy-vton-2 and lucy-vton-3 model IDs

[tomershlasky]

Summary

• Remove lucy-vton-2, lucy-vton-3 and the deprecated alias lucy-2.1-vton-2 from the RealTimeModels / VideoModels literals, MODEL_ALIASES and both model registries in decart/models.py.
• lucy-vton-3.5 and the server-resolved lucy-vton-latest alias are unchanged.
• Example and playground point at lucy-vton-latest; tests updated (deprecation-once test now uses lucy-pro-v2v).

Same shape as #49 (retired Lucy 2 IDs). Mirrors DecartAI/sdk#205. The public literals narrow, so this warrants a minor bump (0.2.0) rather than a patch.

Test plan

• uv run pytest: 86 passed
• uv run ruff check decart tests: clean
• uv run mypy decart: the same 37 pre-existing errors as main, none in models.py

https://claude.ai/code/session_01TNMMxPdhY2U2YZpnbKxZEN

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Note

Medium Risk
Narrowing public model literals is a breaking SDK change for anyone still referencing retired VTON IDs, though that aligns with server-side retirement.

Overview
Retires lucy-vton-2, lucy-vton-3, and the deprecated alias lucy-2.1-vton-2 from the SDK’s typed model surface: they are dropped from RealTimeModels / VideoModels, MODEL_ALIASES, and the realtime/video registries in decart/models.py. lucy-vton-3.5 and server-resolved lucy-vton-latest stay supported.

Docs and dev tooling now steer try-on at the latest alias: the video try-on example and playground realtime list use lucy-vton-latest instead of lucy-vton-3. Tests shed coverage for the removed IDs; the “deprecation warning only once” case now exercises lucy-pro-v2v instead of the removed VTON alias.

Callers still passing the old IDs will fail type checking / model lookup rather than hitting retired job/stream paths—same pattern as prior Lucy ID retirements.

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