feat: implement bio landing page with dash-mantine-components

- Full bio page with hero, summary, tech stack, projects, social links
- MantineProvider theme integration in app.py
- Responsive layout using DMC SimpleGrid
- Added dash-iconify for social link icons
- Updated mypy overrides for DMC/iconify modules

Closes #11

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

portfolio_app/config.py

@@ -5,7 +5,7 @@ from functools import lru_cache
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 
-class Settings(BaseSettings):
+class Settings(BaseSettings):  # type: ignore[misc]
     """Application settings loaded from environment variables."""
 
     model_config = SettingsConfigDict(