feat(lint): replace mypy with ty type checker

[Tranquility2]

Closes #1001

Swaps mypy for Astral's ty as the project's static type checker.
ty is ~20x faster on this codebase (0.25s vs 4.9s locally) and provides clearer diagnostics.

Tooling changes

• pyproject.toml: drop mypy>=1 and types-paramiko>=4 from the lint dep group, add ty.
  Replace the [tool.mypy] block + [[tool.mypy.overrides]] entries with [tool.ty.*] blocks.
  unresolved-import and possibly-missing-submodule are set to ignore to preserve the previous ignore_missing_imports behavior for docker / wrapt / requests / registry.
• Makefile: replace mypy-core / mypy-core-report with ty-core.
• .pre-commit-config.yaml: swap the local mypy hook for a local ty hook.
• .github/workflows/ci-lint.yml: run make ty-core.
• scripts/mypy_report.py: removed (no longer needed; ty's own output is concise).
• README.md: add ty badge.

Code fixes for diagnostics surfaced by ty

• container._transfer_into_container: default mode=0o644 to match with_copy_into_container.
• container.get_wrapped_container / image.get_wrapped_image: annotate return as Optional[...] (they can be None before start()).
• wait_strategies._get_status_tc_container: raise ContainerStartException when the container is not started instead of dereferencing None.
• waiting_utils: use getattr(self.func, "__name__", repr(self.func)) for safer error messages.
• Targeted # ty: ignore[...] for the hasattr-guarded add_note, the Protocol-narrowed container.exec call, the kwargs unpack into docker-py, and the wrapt decorator cast.

Verification

• uv run ty check core/testcontainers → All checks passed!
• make ty-core → passes
• uv run pytest -q core/tests → 121 passed

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.21%. Comparing base (be4c857) to head (9a19a67).

Files with missing lines	Patch %	Lines
core/testcontainers/core/wait_strategies.py	25.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1038      +/-   ##
==========================================
- Coverage   83.29%   83.21%   -0.09%     
==========================================
  Files          16       16              
  Lines        1754     1757       +3     
  Branches      193      194       +1     
==========================================
+ Hits         1461     1462       +1     
- Misses        236      237       +1     
- Partials       57       58       +1     

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