find: -printf: reject an over-large field width instead of panicking

[leeewee]

Fixes #732
Fixes #693

A -printf field width could panic two ways:

• a width above u16::MAX (65535) reached core::fmt's {:>width$}, which caps the width argument at u16::MAX and panics with "Formatting argument out of range" (bug: find -printf panics issues #693);
• a width above usize::MAX was .unwrap()-ed after a failed parse (find panics (parse().unwrap() overflow) on a huge -printf field width #732).

$ mkdir d; touch d/a
$ find d -printf '%70000s\n'                  # #693
thread 'main' panicked at src/find/matchers/printf.rs:611:37:
Formatting argument out of range

$ find d -printf '%99999999999999999999s\n'   # #732
thread 'main' panicked at src/find/matchers/printf.rs:223:45:
called `Result::unwrap()` on an `Err` value: ParseIntError { kind: PosOverflow }

parse_format_width is now fallible and rejects both an unparseable (too-large-for-usize) width and any width above u16::MAX, with a graceful error (exit 1) instead of aborting. Widths up to 65535 still pad as before.

Note on the threshold: this rejects any width above u16::MAX (65535), which is below GNU's -printf width ceiling (glibc's printf pads up to near INT_MAX = 2147483647 and errors with EOVERFLOW above it). 65535 is the limit of Rust's core::fmt width argument, so it's where padding can be done without panicking; widths in 65536..INT_MAX that GNU would pad are rejected here rather than emitting up to gigabytes of padding. This keeps the fix minimal and panic-free — a future change could pad those manually to fully match GNU.

Added an integration test (find_printf_width_too_large).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.87%. Comparing base (795d29a) to head (f0ba464).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #734   +/-   ##
=======================================
  Coverage   91.86%   91.87%           
=======================================
  Files          35       35           
  Lines        7153     7160    +7     
  Branches      375      376    +1     
=======================================
+ Hits         6571     6578    +7     
  Misses        437      437           
  Partials      145      145           

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[codspeed-hq]

Merging this PR will not alter performance

✅ 20 untouched benchmarks

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_{Comparing leeewee:find-fix-printf-width-overflow (f0ba464) with main (795d29a)}