feat: add optional FastMCP skill for building MCP servers

Add FastMCP skill to optional-skills/mcp/fastmcp/ with:
- SKILL.md with workflow, design patterns, quality checklist
- Templates: API wrapper, database server, file processor
- Scaffold CLI script for template instantiation
- FastMCP CLI reference documentation

Moved to optional-skills (requires pip install fastmcp).

Based on work by kshitijk4poor in PR #2096.
Closes #343

optional-skills/mcp/fastmcp/templates/api_wrapper.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+import os
+from typing import Any
+
+import httpx
+from fastmcp import FastMCP
+
+
+mcp = FastMCP("__SERVER_NAME__")
+
+API_BASE_URL = os.getenv("API_BASE_URL", "https://api.example.com")
+API_TOKEN = os.getenv("API_TOKEN")
+REQUEST_TIMEOUT = float(os.getenv("API_TIMEOUT_SECONDS", "20"))
+
+
+def _headers() -> dict[str, str]:
+    headers = {"Accept": "application/json"}
+    if API_TOKEN:
+        headers["Authorization"] = f"Bearer {API_TOKEN}"
+    return headers
+
+
+def _request(method: str, path: str, *, params: dict[str, Any] | None = None) -> Any:
+    url = f"{API_BASE_URL.rstrip('/')}/{path.lstrip('/')}"
+    with httpx.Client(timeout=REQUEST_TIMEOUT, headers=_headers()) as client:
+        response = client.request(method, url, params=params)
+        response.raise_for_status()
+        return response.json()
+
+
+@mcp.tool
+def health_check() -> dict[str, Any]:
+    """Check whether the upstream API is reachable."""
+    payload = _request("GET", "/health")
+    return {"base_url": API_BASE_URL, "result": payload}
+
+
+@mcp.tool
+def get_resource(resource_id: str) -> dict[str, Any]:
+    """Fetch one resource by ID from the upstream API."""
+    payload = _request("GET", f"/resources/{resource_id}")
+    return {"resource_id": resource_id, "data": payload}
+
+
+@mcp.tool
+def search_resources(query: str, limit: int = 10) -> dict[str, Any]:
+    """Search upstream resources by query string."""
+    payload = _request("GET", "/resources", params={"q": query, "limit": limit})
+    return {"query": query, "limit": limit, "results": payload}
+
+
+if __name__ == "__main__":
+    mcp.run()