Implemented complete CRUD (Create, Read, Update, Delete) operations for the web UI:
## Context CRUD:
- Added HandleCreateContext and HandleDeleteContext handlers
- Created modal form for context creation in contexts.html
- Added delete buttons with confirmation dialogs
- Added POST /contexts and POST /contexts/:id/delete routes
- Contexts now support proper position-based ordering
## Todo CRUD:
- Added HandleCreateTodo and HandleDeleteTodo handlers
- Created modal form for todo creation with context selection in todos.html
- Context selection is required (aligned with GTD methodology)
- Added delete buttons for todos with confirmation dialogs
- Added POST /todos and POST /todos/:id/delete routes
- Updated ShowTodos to pass available contexts to template
## RSS Feed:
- Implemented HandleContextFeed handler with RSS 2.0 XML generation
- Added GET /contexts/:id/feed.rss route
- Feed includes all todos for a specific context
- Feed contains todo description, notes, project, and due date info
## Testing:
- Created comprehensive Playwright test suite (test-tracks-crud.js)
- Tests cover: login, context creation, todo creation with context assignment,
todo deletion, context deletion, and RSS feed validation
All code compiles successfully. Ready for end-to-end testing.
