fix: remove return type annotations for MCP SDK 1.25 + Pydantic 2.10 compatibility

- Remove return type annotations from 90 @mcp.tool(), 2 @mcp.resource(),
  and 2 @mcp.prompt() decorated functions to fix PydanticUserError
- Fix %s to $1 in PostgreSQL_create_user (asyncpg syntax)
- Fix .dict() to .model_dump() for Pydantic v2 compatibility

Author: mukul975