Add filterset DSL for test selection

[MatthewMckee4]

Summary

Closes #546.

Replaces -t/--tag and -m/--match with one flag, -E/--filter, that takes an expression language like nextest's filtersets.

karva test -E 'tag(slow)'
karva test -E 'test(/^auth::/) & not tag(flaky)'
karva test -E '(tag(fast) | tag(unit)) - tag(flaky)'

Two predicates: test(...) against the qualified test name, tag(...) against custom tags. Four matcher kinds — =exact, ~substring, /regex/, #glob — with test() defaulting to substring and tag() defaulting to exact. Operators are &, |, not, and - (and-not), with parens for grouping. Keyword spellings and/or/not also work. Multiple -E flags OR together like -t/-m used to.

Old → new:

• -t slow → -E 'tag(slow)'
• -m auth → -E 'test(/auth/)'
• -t slow -m auth → -E 'tag(slow) & test(/auth/)'
• -t '(slow or fast) and not flaky' → -E '(tag(slow) | tag(fast)) - tag(flaky)'

The full table is in docs/usage/filtering.md.

This is a breaking change — -t and -m are gone, not deprecated, per the issue thread.

The parser is in crates/karva_metadata/src/filter.rs, extending the old tag expression parser. Only new dep is globset. Filter application in package_runner::should_skip_variant is now one call instead of two. CLI parse errors get wrapped so you see which flag failed before the detailed reason.

All filter integration tests moved into crates/karva/tests/it/filterset.rs; name_filter.rs is deleted and the filter tests in extensions/tags/custom.rs and parametrize.rs moved over. Tag mechanics tests stay where they were.

Test plan

just test passes and uvx prek run -a is clean.

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

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For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 1 untouched benchmark

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_{Comparing filterset-dsl (2a84e2e) with main (405a0c3)}

[OmChillure]

hey @MatthewMckee4

Now that the filterset DSL (-E/--filter) has been merged in #663, issue #549 seems to be covered without a dedicated skip()

karva test -E 'not test(~slow_)'
karva test -E 'not test(~integration_)'
karva test -E 'not test(~slow_) & not test(~integration_)'

I can see the issue #549 was marked as resolved, or would it be worth adding a dedicated skip(pattern) shorthand predicate to the DSL (e.g. -E 'skip(~slow_)' right? this will a better choice but your call !!

Thank you