fix: align knowledge queries with rg-style remote search

[qiansc]

Summary

• Adopt the pattern, glob, fixed_strings and ignore_case remote search contract with bounded error recovery.
• Improve candidate selection and evidence scope while preserving local grep workflows.
• Regenerate query skill projections without changing the CLI runtime or Wasm.

Validation

• Plugin projection build and skill validation passed.
• Diff checks passed.
• Isolated plugin installation checks passed for three supported hosts.