Add convenience wrappers for todo, calendar, and automation control

[jessica-claude]

Description

Several HA operations are technically possible via hassette's existing call_service() and REST methods, but lack typed convenience wrappers. Adding thin typed APIs for these would improve DX for common automation patterns.

Todo CRUD

Currently requires raw call_service('todo', 'add_item', ...). A typed wrapper would make task-management automations cleaner.

Use cases:

• Add "replace air filter" to a maintenance list when a counter threshold is hit
• Create a grocery item when a pantry sensor trips
• Mark items complete when an automation confirms the task was done

Services to wrap: todo.add_item, todo.update_item, todo.remove_item, todo.get_items
WS-only: todo/item/list (for richer filtering), todo/item/move (reordering)

Calendar Event Read

Hassette already has get_calendar_events() via REST. This may just need better discoverability or typed response models if not already covered.

Use cases:

• Don't run the vacuum if there's a meeting on the calendar
• Pre-heat the house 30 min before an "arrive home" calendar event
• Schedule-aware lighting scenes

Automation Enable/Disable

Currently requires call_service('automation', 'turn_on'/'turn_off', ...). A typed method makes meta-automation patterns more readable.

Use cases:

• Disable motion-light automation when movie mode is on
• Enable security automations when everyone leaves
• Seasonal automation toggling (e.g., holiday lighting schedules)

Services to wrap: automation.turn_on, automation.turn_off, automation.toggle, automation.trigger

Acceptance Criteria

• Typed methods for todo CRUD (add_todo_item, update_todo_item, remove_todo_item, get_todo_items)
• Typed response models for todo items
• Typed methods for automation enable/disable (enable_automation, disable_automation, toggle_automation)
• Verify calendar event API coverage and add typed models if missing
• Tests for all new methods

References

• Identified during MCP gap analysis comparing hassette API surface to HA MCP server capabilities
• Related: Add registry APIs for devices, entities, and areas #285 (registry APIs), Add statistics API support #286 (statistics API), Add Helper CRUD API (input_boolean, counter, timer, etc.) #440 (helper CRUD)