[dbrattli]

Summary

Python already exposed parts of System.Diagnostics.Stopwatch, but its instance methods raised for ordinary repeated calls, elapsed time was unavailable while running, and ElapsedTicks did not use the units declared by Frequency.

This completes the Python mapping and runtime implementation for StartNew, Restart, Elapsed, GetElapsedTime, and IsHighResolution. It uses perf_counter_ns consistently for timestamps and elapsed ticks, accumulates across start/stop cycles, and retains the existing TimerError export for Python callers.

The F# regressions cover running and stopped elapsed time, repeated calls, restart/reset, and timestamp unit conversion on .NET and generated Python.

Python counterpart to #5100.

[github-actions]

Python Type Checking Results (Pyright)

Metric	Value
Total errors	33
Files with errors	4
Excluded files	4
New errors	✅ No

Excluded files with errors (4 files)

These files have known type errors and are excluded from CI. Remove from pyrightconfig.ci.json as errors are fixed.

File	Errors	Status
temp/tests/Python/test_hash_set.py	18	Excluded
temp/tests/Python/test_applicative.py	11	Excluded
temp/tests/Python/test_nested_and_recursive_pattern.py	2	Excluded
temp/tests/Python/fable_modules/thoth_json_python/encode.py	2	Excluded