feat: Add docstrings to generated Python APIs

[razor-x]

Motivation

• Propagate Blueprint descriptions and deprecation metadata into the Python code generator so generated SDK surfaces carry documentation and deprecation signals.
• Produce Sphinx-friendly docstrings for generated route methods, abstract route classes, and resource dataclasses to improve developer ergonomics and enable native Python deprecation notices.
• Ensure deprecated endpoints/params/resources are clearly marked using Python-native mechanisms in generated code.

Description

• Extend the codegen model and plugins to carry description and deprecation fields (codegen/lib/class-model.ts, codegen/lib/routes.ts) and build method/resource docstrings (codegen/lib/layouts/route.ts, codegen/lib/layouts/resources.ts).
• Add docstring templating to the Handlebars layouts so generated abstract classes, concrete routes, method implementations, and dataclass resources include Sphinx-style docs with :param/:type/:returns/:vartype/:ivar and .. deprecated:: directives (changes to codegen/layouts/partials/*.hbs and codegen/layouts/route.hbs).
• Escape and indent doc content safely and include parameter-level deprecation messages and response documentation in method docstrings; resource dataclasses now expose typed :ivar docs for all properties.
• Regenerated Python output under seam/routes and seam/resources to include the new docstrings and deprecation annotations across the SDK surface.

Testing

• Ran TypeScript checks with npm run typecheck (passed).
• Ran linters and formatting with npm run lint and npm run format (passed); code style fixes applied where necessary.
• Ran the generator with npm run generate (generation completed; the run emitted a small set of blueprint warnings about undocumented types but successfully produced regenerated modules).
• Formatted Python and compiled generated modules with PYENV_VERSION=3.12.13 make format and PYENV_VERSION=3.12.13 python -m compileall -q seam (format/compile run in the environment with 3.12.13 succeeded); git diff --check returned clean.
• Attempted PYENV_VERSION=3.12.13 poetry run pytest -q but tests could not run because the environment could not download urllib3 from PyPI (network / package fetch blocked); thus test suite is blocked on dependency fetch and not fully exercised here.

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Codex Task