feat(lists): expose emoji + color in get_lists + create_list (v0.5.1)

get_lists now includes emoji and color fields per list entry.
create_list response also returns emoji and color from the API.

Field name verification (FW_DEBUG=1, 2026-04-16):
- emoji: API returns "" when unset -> normalised to null
- color: API omits key when unset -> normalised to null
- Both fields present in taskgettasklists and taskcreatelist responses

SPEC.md: taskgettasklists documented with full response structure
         and emoji/color normalisation notes.
         taskcreatelist response updated with emoji + color fields.

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

CLAUDE.md

@@ -37,8 +37,9 @@ und wird in Claude Desktop eingebunden.
 ## Roadmap
 
 - v0.4.x: Kategorie-Management, Task-Felder (due_date, assignee, list_id) ✓
-- v0.5.x: Listen-Management (create_list, delete_list) ← aktuell
-- v0.5.1: update_list (Umbenennen), Sharing-Verwaltung
+- v0.5.x: Listen-Management (create_list, delete_list) ✓
+- v0.5.1: emoji + color in get_lists / create_list ← aktuell
+- v0.5.2: update_list (Umbenennen, emoji/color ändern), Sharing-Verwaltung
 - v0.6.x: Erinnerungen + Wiederholungen (Premium-Account erforderlich)
 - v2.0: Schreibzugriff auf Wall-Posts (Erstellen, Kommentieren)