mutation-testing: verify source files with find, not a ** glob (#282)

The "Verify patterns" step under No Mutants Generated ran
`ls src/**/*.rs` to answer whether source files exist where the include
pattern points. Whether `**` recurses depends on the shell: zsh expands
it, bash does not unless globstar is set, and the bash 3.2 macOS ships
has no globstar option to set. Under bash the glob degrades to
`src/*/*.rs`. On a tree holding src/top.rs, src/a/one.rs,
src/a/b/two.rs and src/a/b/c/three.rs, find reports four files and the
ls form reports one.

So the command existed to tell the user their include pattern was fine
and instead under-reported the files that matched it, on some machines
but not others. The dropped files read as "include pattern doesn't
match" — the first entry in the Common causes list directly below it —
and send someone off to edit a pattern that was already correct.

find behaves identically in every shell and exits 0 when nothing
matches rather than erroring.

Only the unquoted shell glob changed. The `**` in mewt.toml include
values and in quoted `--target 'src/auth/**/*.rs'` arguments is mewt's
own glob syntax, expanded by mewt rather than the shell, and is correct
as written; the note says so to keep the fix from spreading there.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

plugins/mutation-testing/.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "mutation-testing",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "Configures mewt or muton mutation testing campaigns — scopes targets, tunes timeouts, and optimizes long-running runs. Use when the user mentions mewt, muton, mutation testing, or wants to configure or optimize a mutation testing campaign.",
   "author": {
     "name": "Trail of Bits",

plugins/mutation-testing/skills/mutation-testing/workflows/configuration.md

@@ -277,9 +277,11 @@ mewt print mutations --language rust
 **Verify patterns:**
 ```bash
 mewt print config
-ls src/**/*.rs  # Do files exist and match include patterns?
+find src -name '*.rs' | head  # Do source files exist where include points?
 ```
 
+`find`, not `ls src/**/*.rs`. Whether `**` recurses depends on the shell: zsh expands it, bash does not unless `globstar` is set, and the bash 3.2 that macOS ships has no `globstar` option to set. So the `ls` form degrades to `src/*/*.rs` under bash — given `src/top.rs`, `src/a/one.rs`, and `src/a/b/two.rs` it lists only `src/a/one.rs` — while the same line is correct under zsh. A diagnostic that under-reports on some machines and not others is worse than none: the files it drops read as "the include pattern doesn't match," sending you to edit a pattern that was already right. `find` behaves identically in every shell and exits 0 when nothing matches, instead of erroring. Keep the `**` in `mewt.toml`, where mewt expands it rather than the shell.
+
 **Common causes:**
 - Include pattern doesn't match files
 - Ignore pattern too broad (e.g., `"test"` matches `test_utils.rs`)