fix: SQLAlchemy JSON mutation detection for saved ideas and approved examples

SQLAlchemy doesn't detect in-place mutations on JSON columns (same object
reference). Fixed all JSON write operations to create new list/dict objects:
- save_idea: [new_idea] + old_ideas instead of ideas.insert()
- delete_idea: new filtered list
- mark_idea_used: new list with copied dicts
- approve_post: dict(examples) for content_rules

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/routers/content.py

@@ -334,7 +334,7 @@ def approve_post(
             })
             # Keep only last 5
             examples["approved_examples"] = approved_examples[-5:]
-            character.content_rules = examples
+            character.content_rules = dict(examples)  # new dict for SQLAlchemy change detection
             character.updated_at = datetime.utcnow()
 
     db.commit()
@@ -487,7 +487,7 @@ def save_idea(
         .filter(SystemSetting.key == "saved_ideas", SystemSetting.user_id == current_user.id)
         .first()
     )
-    ideas = setting.value if setting and isinstance(setting.value, list) else []
+    old_ideas = list(setting.value) if setting and isinstance(setting.value, list) else []
 
     new_idea = {
         "id": str(uuid.uuid4())[:8],
@@ -496,13 +496,13 @@ def save_idea(
         "saved_at": datetime.utcnow().isoformat() + "Z",
         "used": False,
     }
-    ideas.insert(0, new_idea)
+    new_ideas = [new_idea] + old_ideas  # new list — forces SQLAlchemy to detect change
 
     if setting:
-        setting.value = ideas
+        setting.value = new_ideas
         setting.updated_at = datetime.utcnow()
     else:
-        db.add(SystemSetting(key="saved_ideas", value=ideas, user_id=current_user.id))
+        db.add(SystemSetting(key="saved_ideas", value=new_ideas, user_id=current_user.id))
     db.commit()
     return new_idea
 
@@ -522,11 +522,11 @@ def delete_idea(
     if not setting or not isinstance(setting.value, list):
         raise HTTPException(status_code=404, detail="Idea not found")
 
-    ideas = [i for i in setting.value if i.get("id") != idea_id]
-    if len(ideas) == len(setting.value):
+    new_ideas = [i for i in setting.value if i.get("id") != idea_id]
+    if len(new_ideas) == len(setting.value):
         raise HTTPException(status_code=404, detail="Idea not found")
 
-    setting.value = ideas
+    setting.value = new_ideas  # new list object for SQLAlchemy change detection
     setting.updated_at = datetime.utcnow()
     db.commit()
     return {"ok": True}
@@ -547,13 +547,19 @@ def mark_idea_used(
     if not setting or not isinstance(setting.value, list):
         raise HTTPException(status_code=404, detail="Idea not found")
 
+    updated = []
+    found = False
     for idea in setting.value:
-        if idea.get("id") == idea_id:
-            idea["used"] = True
-            break
-    else:
+        copy = dict(idea)
+        if copy.get("id") == idea_id:
+            copy["used"] = True
+            found = True
+        updated.append(copy)
+
+    if not found:
         raise HTTPException(status_code=404, detail="Idea not found")
 
+    setting.value = updated  # new list for SQLAlchemy change detection
     setting.updated_at = datetime.utcnow()
     db.commit()
     return {"ok": True}