chore: add D212 lint rule to enforce Google-style docstrings (#1892)

examples/fastmcp/unicode_example.py

@@ -1,5 +1,4 @@
-"""
-Example FastMCP server that uses Unicode characters in various places to help test
+"""Example FastMCP server that uses Unicode characters in various places to help test
 Unicode handling in tools and inspectors.
 """
 
@@ -10,8 +9,7 @@ mcp = FastMCP()
 
 @mcp.tool(description="🌟 A tool that uses various Unicode characters in its description: á é í ó ú ñ 漢字 🎉")
 def hello_unicode(name: str = "世界", greeting: str = "¡Hola") -> str:
-    """
-    A simple tool that demonstrates Unicode handling in:
+    """A simple tool that demonstrates Unicode handling in:
     - Tool description (emojis, accents, CJK characters)
     - Parameter defaults (CJK characters)
     - Return values (Spanish punctuation, emojis)