[egorsmkv]

Python str()/repr() currently build an intermediate Rust String before constructing Unicode. Replace all 14 methods with checked stack-buffer formatting and direct PyString returns while preserving textual output. Rust parsing/arithmetic already use borrowed inputs and inline Copy values; a counting-allocator regression test guards these paths. Python output objects still allocate and copy bytes.

Add pinned Ruff 0.16.10 and Pyright 1.1.414 development tools, project configuration targeting Python 3.10, and a dedicated CI job for linting, formatting and type checking all Python source and stubs. Format examples, tests, benchmark and stubs; replace wildcard exports with explicit re-exports. Put native extension declarations in fasttime.pyi and add the comparison operators already supported at runtime. Only missing native implementation-source diagnostics are disabled; missing-import checks remain enabled.

Fix the unix_timestamps example's unsupported DateTime width formatting by using !s and run every example in the Python CI matrix.

Validation:

• Ruff check and format --check passed for all 11 Python/stub files.
• Pyright: 0 errors, 0 warnings.
• Built and installed a release CPython 3.12 wheel; 38 Python tests and all five examples passed; benchmark runs successfully.
• Rust tests passed with and without default features (20 tests each); allocation regression measured 0 Rust heap allocations on covered paths; clippy and cargo fmt passed.
• Combined revision 5160673: Test CI passed (Ruff/Pyright, Rust, Python 3.10–3.14 tests and examples); Windows wheel CI passed all eight Windows jobs, including 3.14t/3.15t.

Local release-wheel formatting microbenchmarks on CPython 3.12/Linux favored stack formatting in both execution orders (~8–33% lower latency across measured cases); shared-host timings vary. Reproduce with python/benchmarks/string_formatting.py.