feat: add Task CRUD tools – create, update, toggle, delete (v0.4.0)

Implements four new MCP write tools via taskcreate2, taskupdate2,
taskmark, and metadelete endpoints. Confirmation prompts noted in
docstrings for destructive/mutating operations. Body parameters
documented in SPEC.md as pending verification via FW_DEBUG=1.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -1,12 +1,22 @@
 # mcp-familywall
 
-MCP server for [Family Wall](https://www.familywall.com) -- read your family's circles, lists, and tasks directly from Claude.
+MCP server for [Family Wall](https://www.familywall.com) -- read and manage your family's circles, lists, and tasks directly from Claude.
 
-## Features (v1.0 -- read-only)
+## Features (v0.4.0)
+
+### Read
 
 - `get_circles` -- list all family circles
 - `get_lists` -- list all task lists (optionally filtered by circle)
 - `get_tasks` -- list tasks in a specific list
+- `get_activities` -- list recent wall activities
+
+### Write (with confirmation prompt)
+
+- `create_task` -- create a new task in a list
+- `update_task` -- update the text/description of an existing task
+- `toggle_task` -- mark a task complete or reopen it
+- `delete_task` -- permanently delete a task
 
 ## Requirements