pctx-py: add ty type checking, split Makefile, refine @tool

[eliasposen]

Summary

• Type checking with ty: added ty as a dev dep, fixed all type errors it surfaced in _client.py, _convert.py, _tool.py, _websocket_client.py, descriptions/init.py, and models.py. Includes a real bug fix in _websocket_client.execute_typescript — ExecuteCodeParams(style=disclosure) was silently dropped by pydantic, so the websocket path always used CATALOG regardless of the caller's disclosure arg.
• Makefile split: moved Python-specific targets out of the root Makefile into a new pctx-py/Makefile. Added install, lint, typecheck, and check (lint+typecheck+test) targets.
• CI: renamed the lint job to check, added a Type check step, and gated the static-analysis steps on !cancelled() && install.outcome == 'success' so a single CI run surfaces all formatting/lint/typecheck issues at once.
• @tool decorator polish: input_schema accepts a Pydantic BaseModel or JSON Schema dict; output_schema accepts a Python type / typing construct or JSON Schema dict; name is now keyword-only.
• Changelog: added pctx-py/CHANGELOG.md with backfilled history.

Test plan

• make -C pctx-py check passes locally
• CI check job runs format / lint / typecheck and surfaces all failures in one run
• CI test matrix passes on 3.10–3.13
• Verify disclosure arg now reaches the websocket execute path (fixed bug)

🤖 Generated with Claude Code

[pk8189]

type checking good