refactor(tools): consolidate LLM tools from 42 to 38

Merge create_task into create_note (set status='todo' for tasks, omit
for notes), merge delete_task into delete_note, consolidate entity
tools (create/update_person → save_person, create/update_place →
save_place), rename get_note → read_note with clearer descriptions,
move calculate out of rag.py into utility.py, and extract shared
duplicate detection into check_duplicate() helper.

Updates all downstream references in generation_task.py, quick_capture.py,
ToolCallCard.vue, and WorkspaceView.vue.

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

src/fabledassistant/routes/quick_capture.py

@@ -21,7 +21,7 @@ quick_capture_bp = Blueprint("quick_capture", __name__, url_prefix="/api/quick-c
 
 # Tools offered to the quick-capture endpoint. Excludes destructive ops,
 # read-only queries, and conversational-only tools.
-_CAPTURE_TOOL_NAMES = {"create_note", "create_task", "create_event", "update_note", "research_topic"}
+_CAPTURE_TOOL_NAMES = {"create_note", "create_event", "update_note", "research_topic"}
 
 _SYSTEM_PROMPT = """\
 Today is {today}. You are a quick-capture assistant. The user has sent a short \