Fix grep literal matching for regex metacharacters

[r-sandeep]

Summary

• escape regex metacharacters in the user-supplied grep pattern before matching
• preserve case-sensitive literal matching and the existing colorText(match, "files") output path
• keep the existing usage, missing-file, and id_rsa easter-egg behavior unchanged
• add focused VM-harness regression tests for punctuation, literal dots, ordinary patterns, missing arguments, and missing files

Validation

• npm test — passed (7 test files, 125 tests)
• npm run build — passed
• clean-checkout npm test — passed
• clean-checkout npm run build — passed

Scope

The final diff contains only:

• config/commands.js
• tests/commands.test.js

Approvals and review

All recorded policy decisions allow the change, all prior approvals are decided, and no approvals remain open. Independent verification and adversarial review found no unresolved defect or delivery risk.

ASD references

• Workflow run: workflow_run_3868a5bd37a84a0fabb2f90c43089bf6
• Work packet task: task_4f2c33855df54dc7adea1afdf3bf3d00
• Lane: enterprise_bug_fix_fast_v1