chore: switch default AI backend to Mistral and support .env.local override

AI_TEXT_MODEL and AI_VISION_MODEL now point to the Mistral vars by default.
SERP_API_KEY removed. All docker-compose services load .env.local as an
optional overlay so local credentials don't have to go into .env.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.env

@@ -23,9 +23,8 @@ MISTRAL_VISION_MODEL=pixtral-12b-2409
 MISTRAL_TEXT_MODEL=mistral-large-latest
 
 # Active backend — point these at OLLAMA_* or MISTRAL_* vars
-AI_TEXT_MODEL=${OLLAMA_TEXT_MODEL}
-AI_VISION_MODEL=${OLLAMA_VISION_MODEL}
-SERP_API_KEY=
+AI_TEXT_MODEL=${MISTRAL_TEXT_MODEL}
+AI_VISION_MODEL=${MISTRAL_VISION_MODEL}
 
 EBAY_CLIENT_ID=
 EBAY_CLIENT_SECRET=

docker-compose.yml

@@ -13,7 +13,11 @@ services:
         condition: service_healthy
       redis:
         condition: service_healthy
-    env_file: .env
+    env_file:
+      - path: .env
+        required: true
+      - path: .env.local
+        required: false
 
   caddy:
     image: caddy:2-alpine
@@ -62,7 +66,11 @@ services:
     depends_on:
       - postgres
       - redis
-    env_file: .env
+    env_file:
+      - path: .env
+        required: true
+      - path: .env.local
+        required: false
     restart: unless-stopped
 
   worker-orders:
@@ -78,7 +86,11 @@ services:
     depends_on:
       - postgres
       - redis
-    env_file: .env
+    env_file:
+      - path: .env
+        required: true
+      - path: .env.local
+        required: false
     restart: unless-stopped
 
   worker-channel:
@@ -94,7 +106,11 @@ services:
     depends_on:
       - postgres
       - redis
-    env_file: .env
+    env_file:
+      - path: .env
+        required: true
+      - path: .env.local
+        required: false
     restart: unless-stopped
 
   cron:
@@ -113,7 +129,11 @@ services:
       - .:/var/www
     depends_on:
       - postgres
-    env_file: .env
+    env_file:
+      - path: .env
+        required: true
+      - path: .env.local
+        required: false
     restart: unless-stopped
 
 volumes: