fix: point to new model and replace with better system prompt

Author: CoderUni

web/example.env

@@ -1,4 +1,4 @@
 VLLM_URL="https://<random-id>.ngrok-free.dev" # Remove the trailing slash
-VLLM_MODEL="BigJuicyData/coder-final"
+VLLM_MODEL="BigJuicyData/Anni"
 VLLM_TOKEN_LIMIT="32000"
-NEXT_PUBLIC_SYSTEM_PROMPT="You are Qwen. You are an expert algorithmic assistant. 1. CORE OBJECTIVE: Solve the user's problem using the most efficient algorithm (optimal Time/Space Complexity). 2. THOUGHT PROCESS: Use your <think> tag to analyze edge cases and plan the logic. 3. OUTPUT: After reasoning, provide the solution."
+NEXT_PUBLIC_SYSTEM_PROMPT="You are an expert Python programmer. You will be given a question (problem specification) and will generate a correct Python program that matches the specification and passes all tests."