* fix(sandbox): search long lines for literal grep patterns
* test(sandbox): cover literal long lines across providers
* fix(sandbox): bound case-insensitive literal grep work
Replace repeated-prefix regex searches with KMP over single-character Unicode case matches. Keep local long-line literal results and existing regex and preview limits. Add a subprocess-deadline regression for the review counterexample and case-semantics coverage.
* docs(sandbox): keep grep guidance within inherited size limit
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
