Add .agents/commands as a search path for tasks

[Copilot]

• Understand the codebase and search path structure
• Run linter and build to verify current state
• Add .agents/commands to taskSearchPaths in pkg/codingcontext/paths.go
• Add test for tasks in .agents/commands directory
• Verify tests pass
• Manually verify the CLI works with .agents/commands
• Update documentation
  • docs/reference/search-paths.md - Added .agents/commands to Task File Search Paths
  • docs/how-to/create-tasks.md - Mentioned .agents/commands as an alternative location
  • README.md - Updated Supported Coding Agents and File Search Paths sections
• Run code review and fix any issues
• Run CodeQL security check

Original prompt

Add .agents/commands as a search path for tasks (aka "commands")

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[alexec]

@copilot Update the docs of course.

[Copilot]

@copilot Update the docs of course.

Updated the documentation in commit 85b3a95:

• docs/reference/search-paths.md: Added .agents/commands/ to Task File Search Paths section
• docs/how-to/create-tasks.md: Mentioned .agents/commands as an alternative location
• README.md: Updated Supported Coding Agents and File Search Paths sections