Refactor code for improved readability and consistency

- Cleaned up whitespace and formatting in various files including http.py, language.py, logger.py, safe_exec.py, and SQL migration scripts.
- Consolidated import statements and removed unnecessary blank lines.
- Updated logging configuration for better clarity.
- Enhanced the safe execution code with improved error handling and logging.
- Removed commented-out code and unnecessary variables in backfill_zero_trades.py and other scripts.
- Added a pyproject.toml for Ruff and Vulture configuration.
- Introduced requirements-dev.txt for development dependencies.
- Removed commented-out stock entries in init.sql for cleaner migration scripts.

backend_api_python/app/routes/ai_chat.py

@@ -3,44 +3,41 @@ AI chat API routes (optional).
 Currently kept as a minimal compatibility layer for legacy frontend calls.
 """
 
-from flask import Blueprint, request, jsonify
+from flask import Blueprint, jsonify, request
 
 from app.utils.logger import get_logger
 
 logger = get_logger(__name__)
 
-ai_chat_bp = Blueprint('ai_chat', __name__)
+ai_chat_bp = Blueprint("ai_chat", __name__)
 
 
-@ai_chat_bp.route('/chat/message', methods=['POST'])
+@ai_chat_bp.route("/chat/message", methods=["POST"])
 def chat_message():
     """
     Minimal placeholder for legacy chat.
     Return a friendly message instead of 404, so the UI can evolve gradually.
     """
     data = request.get_json() or {}
-    msg = (data.get('message') or '').strip()
+    msg = (data.get("message") or "").strip()
     if not msg:
-        return jsonify({'code': 0, 'msg': 'Missing message', 'data': None}), 400
-    return jsonify({
-        'code': 1,
-        'msg': 'success',
-        'data': {
-            'reply': 'Chat API is not implemented yet in local-only mode.',
-            'echo': msg
+        return jsonify({"code": 0, "msg": "Missing message", "data": None}), 400
+    return jsonify(
+        {
+            "code": 1,
+            "msg": "success",
+            "data": {"reply": "Chat API is not implemented yet in local-only mode.", "echo": msg},
         }
-    })
+    )
 
 
-@ai_chat_bp.route('/chat/history', methods=['GET'])
+@ai_chat_bp.route("/chat/history", methods=["GET"])
 def get_chat_history():
     """Return empty history (compatibility stub)."""
-    return jsonify({'code': 1, 'msg': 'success', 'data': []})
+    return jsonify({"code": 1, "msg": "success", "data": []})
 
 
-@ai_chat_bp.route('/chat/history/save', methods=['POST'])
+@ai_chat_bp.route("/chat/history/save", methods=["POST"])
 def save_chat_history():
     """No-op save (compatibility stub)."""
-    return jsonify({'code': 1, 'msg': 'success', 'data': None})
-
-
+    return jsonify({"code": 1, "msg": "success", "data": None})