fix: add missing tools field to test-writer-fixer agent

[xiaolai]

Automated audit: This PR was generated by NLPM, a natural language programming linter, running via claude-code-action. Please evaluate the diff on its merits.

Bug

test-writer-fixer/agents/test-writer-fixer.md has a valid name, description, and color in its frontmatter but is missing the tools field entirely:

---
name: test-writer-fixer
description: ...
color: cyan
---

In Claude Code, agents without a declared tools field have an undefined tool budget. The behavior varies across versions — some fall back to a default set, others inherit nothing. For an agent whose entire purpose is to run tests, edit test files, and read source code, this is a functional bug: the agent may silently lack the tools it needs to operate.

Fix

Added the tools field listing the tools this agent needs:

tools:
  - Bash
  - Read
  - Write
  - Edit
  - Glob
  - Grep

Rationale per tool:

• Bash — run test runners (jest, pytest, mocha, etc.) and check test results
• Read — read source files and existing test files
• Write — create new test files
• Edit — modify failing or brittle tests
• Glob — discover test files by pattern
• Grep — search for imports, function names, and test patterns

Impact

Without this fix, the agent's tool access is implementation-defined and may break silently as Claude Code evolves. Declaring tools explicitly makes the contract clear and ensures consistent behavior.