[FEATURE] Add IntelliJ / JetBrains as an MCP target

[kkadete]

Is your feature request related to a problem? Please describe.

APM's promise is that "one file describes every agent's context; one command reproduces it everywhere" — but developers using JetBrains IDEs (IntelliJ IDEA) with are cannot use the MCP config.

GitHub Copilot for JetBrains reads MCP server configuration from a user-scope config file. The path are:

Platform	Path
Windows	%LOCALAPPDATA%\github-copilot\intellij\mcp.json
macOS	~/Library/Application Support/github-copilot/intellij/mcp.json (unverified — follows standard macOS app-data conventions)
Linux	~/.local/share/github-copilot/intellij/mcp.json (unverified — follows data dir conventions)

The config uses a "servers" top-level key (not "mcpServers"), matching the format documented in the official GitHub Copilot MCP docs for JetBrains:

{
  "servers": {
    "memory": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-memory"]
    }
  }
}

apm install --mcp currently wires MCP servers into VS Code, Copilot CLI, Codex, Claude, Cursor, Gemini, OpenCode, and Windsurf — but not JetBrains IDEs. This forces JetBrains users to manually duplicate MCP configuration into the Copilot-for-IntelliJ config file after every apm install, which is error-prone and breaks reproducibility.

The IDE & Tool Integration — Roadmap already lists this as planned:

JetBrains IDE support: Native integration with IntelliJ, PyCharm, WebStorm, and other JetBrains IDEs

Only MCP configuration is missing. All other Copilot primitives (instructions, prompts, agents, skills) already work in JetBrains IDEs through the .github/ directory that the existing copilot target deploys.

Describe the solution you'd like

Add intellij as a new MCP runtime target so that apm install (and apm install --mcp) also writes MCP server entries to the JetBrains-specific Copilot MCP config path.

Expected behavior:

• apm install auto-detects whether the JetBrains Copilot config directory exists and wires MCP servers into it alongside the other detected clients.
• apm install --runtime intellij explicitly targets IntelliJ only.

Describe alternatives you've considered

• Manual copy: Manually duplicate .vscode/mcp.json content into the JetBrains Copilot path after every apm install. Error-prone, not reproducible, defeats APM's purpose.
• Symlink: Symlink the IntelliJ config to .vscode/mcp.json. Fragile across OSes and requires admin elevation on Windows.