feat: create_category + delete_category tools (v0.4.11)

Verified via systematic FW_DEBUG=1 probing:
- taskcategoryput: requires 'name'; optional 'emoji' (Unicode or string code)
  accepted as-is. 'listId' param has no per-list effect — categories are
  family-wide.
- taskcategorydelete: uses 'id' param (not 'metaId'), returns r='true'.

Changes:
- create_category(list_id, name, icon=None): creates custom category via
  taskcategoryput; icon maps to 'emoji' API param
- delete_category(category_id): safety check via accgetallfamily looks up
  rights.canDelete='true'; system categories (rights.canDelete=null) are
  refused with a clear error
- get_categories: now exposes 'custom' bool field (rights.canDelete='true')
  so callers can identify deletable categories
- SPEC.md: document taskcategoryput + taskcategorydelete params, responses,
  error formats, and system-category protection behaviour

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

CLAUDE.md

@@ -23,15 +23,16 @@ eingebunden.
 
 ## Aktueller Stand
 
-### Implementierte Tools (v0.4.10)
+### Implementierte Tools (v0.4.11)
 
 | Kategorie | Tools |
 |---|---|
 | Kreise | `get_circles`, `get_members` |
 | Listen | `get_lists` |
-| Tasks (Lesen) | `get_tasks` (inkl. `category_id`), `get_categories` |
+| Tasks (Lesen) | `get_tasks` (inkl. `category_id`), `get_categories` (inkl. `custom`-Flag) |
 | Wall | `get_activities`, `like_post` |
 | Tasks (Schreiben) | `create_task` (inkl. `category_id`), `update_task` (inkl. `category_id`), `toggle_task`, `delete_task` |
+| Kategorien (Schreiben) | `create_category` (inkl. `icon`), `delete_category` (System-Kategorien geschützt) |
 
 
 ## Roadmap