Fix CSS copying and processing with Trunk

- Use data-trunk directive for CSS processing instead of manual copy
- Enable automatic content hashing and cache busting for styles.css
- Remove unused CalendarInfo import to fix compiler warning
- Simplify Trunk.toml by removing redundant copy configuration

This ensures styles.css is properly copied and processed on every build
with automatic cache invalidation when styles change.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Trunk.toml

@@ -14,6 +14,3 @@ address = "127.0.0.1"
 port = 8080
 open = false
 
-[[copy]]
-from = "styles.css"
-to = "dist/"