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/services/tools/_helpers.py

@@ -75,3 +75,50 @@ def fuzzy_title_match(title: str, candidates, threshold: float = 0.82):
         if r >= threshold and r > best_r:
             best, best_r = c, r
     return best, best_r
+
+
+async def check_duplicate(
+    user_id: int,
+    title: str,
+    body: str,
+    is_task: bool,
+    confirmed: bool,
+) -> dict | None:
+    """Check for exact, fuzzy, and semantic duplicates. Returns error dict or None."""
+    from fabledassistant.services.notes import list_notes
+
+    item_label = "task" if is_task else "note"
+
+    existing, _ = await list_notes(user_id=user_id, q=title, is_task=is_task, limit=1)
+    exact = next((n for n in existing if n.title.lower() == title.lower()), None)
+    if exact is not None:
+        return {
+            "success": False,
+            "error": f"A {item_label} titled '{title}' already exists (id: {exact.id}). Use update_note to modify it instead of creating a duplicate.",
+        }
+
+    clean_q = _PUNCT_RE.sub(" ", title).strip()
+    candidates, _ = await list_notes(user_id=user_id, q=clean_q, is_task=is_task, limit=20)
+    near, ratio = fuzzy_title_match(title, candidates)
+    if near is not None:
+        return {
+            "success": False,
+            "requires_confirmation": True,
+            "similar_note": {"id": near.id, "title": near.title},
+            "error": f"A {item_label} with a very similar title '{near.title}' already exists (similarity: {ratio:.0%}). Ask the user to confirm before creating a separate entry.",
+        }
+
+    if not confirmed and len(body.strip()) >= 80:
+        from fabledassistant.services.embeddings import semantic_search_notes as _ssn
+        sem_query = f"{title}\n{body}".strip()
+        sem_hits = await _ssn(user_id, sem_query, limit=3, threshold=0.90, is_task=is_task)
+        if sem_hits:
+            best_score, best_note = sem_hits[0]
+            return {
+                "success": False,
+                "requires_confirmation": True,
+                "similar_note": {"id": best_note.id, "title": best_note.title},
+                "error": f"A {item_label} with very similar content exists: '{best_note.title}' (semantic similarity: {best_score:.0%}). Ask the user to confirm before creating a separate entry.",
+            }
+
+    return None