Add glob tool for file search by name pattern

Summary

Add a glob tool that finds files by name pattern within the workspace. Essential for discovering project structure and locating files.

Motivation

A coding agent needs to answer questions like "find all Go test files", "where is the main.go", "list all YAML configs." The exec tool can run find, but a dedicated tool provides:

• Workspace boundary enforcement
• Structured output (sorted file list)
• No shell injection risk
• Consistent cross-platform behavior

Proposed interface

{
  "name": "glob",
  "parameters": {
    "pattern": "string — glob pattern, e.g. '**/*.go', 'cmd/*/main.go'",
    "path": "string — optional subdirectory to search (default: workspace root)",
    "max_results": "integer — maximum files to return (default: 100)"
  }
}

Implementation notes

• Use github.com/bmatcuk/doublestar/v4 for ** support (Go's filepath.Glob doesn't support **)
• Or: shell out to fd if available, fall back to filepath.Walk + filepath.Match
• Enforce workspace boundary (same logic as read_file)
• Respect .gitignore if in a git repo
• Sort results by path for deterministic output
• Return one file path per line

Related

• Part of the coding agent capabilities gap analysis
• Pairs with edit_file (#26) and grep (#27) for code navigation + editing workflow
• #7 — Specialized Dockerfiles (coding flavor would bundle fd)

Start by tracing the existing read_file workspace-boundary logic, then review the related edit_file (#26) and grep (#27) tools for interface conventions. Define the glob tool around the proposed pattern, path, and max_results parameters; done means workspace-safe, deterministic, gitignore-aware file paths with cross-platform behavior.