fix(docs): really fix the links in Advent of CALM

[markscott-ms]

and make dev mirror prod behaviour

Description

Okay, so astro can be annoying. In prod (disted) mode, we have pages going to directories, and it redirects requests for /day/2 to /day/2/.

In dev it doesn't do that redirect, it serves the content on both routes.

This is an absolute pain for relative links.

This PR fixes it, and also disables the non-directory route in dev.

Type of Change

• [X] 🐛 Bug fix (non-breaking change which fixes an issue)
• [ ] ✨ New feature (non-breaking change which adds functionality)
• [ ] 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [X] 📚 Documentation update
• [ ] 🎨 Code style/formatting changes
• [ ] ♻️ Refactoring (no functional changes)
• [ ] ⚡ Performance improvements
• [ ] ✅ Test additions or updates
• [ ] 🔧 Chore (maintenance, dependencies, CI, etc.)

Affected Components

• [ ] CLI (cli/)
• [ ] Shared (shared/)
• [ ] CALM Widgets (calm-widgets/)
• [ ] CALM Hub (calm-hub/)
• [ ] CALM Hub UI (calm-hub-ui/)
• [X] Documentation (docs/)
• [ ] VS Code Extension (calm-plugins/vscode/)
• [ ] Dependencies
• [ ] CI/CD

Commit Message Format ✅

Testing

• [X] I have tested my changes locally
• [ ] I have added/updated unit tests
• [X] All existing tests pass

Checklist

• [X] My commits follow the conventional commit format
• [ ] I have updated documentation if necessary
• [ ] I have added tests for my changes (if applicable)
• [X] My changes follow the project's coding standards