test: fix format string lint runner

[nexicturbo]

Bounty submission for #32.

This makes test/lint/lint-format-strings.py runnable and green in this repository.

Changes:

• Invoke run-lint-format-strings.py through the active Python interpreter so the lint works on Windows as well as Unix-like shells.
• Move the excluded-file regex into a named pattern.
• Update the tidy example exclusion for Bitgesell's contrib/devtools/BGL-tidy/example_logprintf.cpp path.
• Exclude src/precompute_ecmult_gen.c, whose generated secp precompute formatter uses PRIx32 literal concatenation plus macro-expanded comma-separated arguments that this static checker cannot model.

Verification:

• python test\lint\lint-format-strings.py
• python -m py_compile test\lint\lint-format-strings.py test\lint\run-lint-format-strings.py
• git diff --check

Payment details can be provided after maintainer approval.

[nexicturbo]

Quick status refresh for bounty review.

This PR remains open, non-draft, and mergeable. Scope is limited to making test/lint/lint-format-strings.py runnable and green on the current Bitgesell tree by:

• invoking the helper through the active Python interpreter
• updating the Bitgesell BGL-tidy exclusion
• excluding the generated secp precompute source false positive

Validation previously run:

• python test\lint\lint-format-strings.py
• python -m py_compile test\lint\lint-format-strings.py test\lint\run-lint-format-strings.py
• git diff --check

No contributor-side revision is pending unless maintainers want a focused adjustment.