Add Brave web search agentic workflow

[Copilot]

This PR adds a new agentic workflow called "brave" that enables web search capabilities using the Brave search engine via the Brave MCP server.

Overview

The workflow responds to /brave commands in issue comments and performs web searches based on the issue context, returning formatted search results as a comment.

Key Features

• Trigger: Responds to /brave command in issue comments only
• MCP Integration: Uses @brave/brave-search-mcp-server for web search functionality
• Context-Aware: Analyzes issue/PR content and the triggering comment to formulate targeted searches
• Safe Outputs: Uses the safe-outputs pattern for secure comment creation with minimal permissions
• Security: Follows minimal permissions principle (contents: read, actions: read)

Implementation Details

The workflow is configured with:

• Engine: Copilot
• Timeout: 10 minutes
• MCP Server: Brave search (stdio) via npx -y @brave/brave-search-mcp-server
• Authentication: Uses BRAVE_API_KEY secret
• Response: Posts up to 1 comment with formatted search results

Usage

To use this workflow:

1. Add BRAVE_API_KEY secret to the repository settings
2. Comment /brave on any issue to trigger the search agent
3. The agent analyzes the issue context and performs relevant web searches
4. Search results are posted as a formatted comment on the issue

Files Added

• .github/workflows/brave.md - Workflow definition (123 lines)
• .github/workflows/brave.lock.yml - Compiled GitHub Actions workflow (2941 lines)

All tests pass and the workflow has been validated with the full test suite.

Original prompt

Add an agentic workflow "brave" that runs a web search using the brave mcp (@brave/brave-search-mcp-server) and the current context. Executes only as a issue-comment and responds as a comment.

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