feat: use correct mistral-large-latest model ID in fallback cycles

backend.py

@@ -1991,7 +1991,7 @@ async def execute_build_cycle(project_name: str, goal: str):
         try:
             if mistral_client:
                 res = await mistral_client.chat.completions.create(
-                    model="mistralai/mistral-large-2-instruct",
+                    model="mistral-large-latest",
                     messages=[{"role": "user", "content": plan_prompt}],
                     max_tokens=300
                 )
@@ -2127,7 +2127,7 @@ async def execute_eternity_cycle(project_name: str, goal: str):
         try:
             if mistral_client:
                 res = await mistral_client.chat.completions.create(
-                    model="mistralai/mistral-large-2-instruct",
+                    model="mistral-large-latest",
                     messages=[{"role": "user", "content": plan_prompt}],
                     max_tokens=300
                 )