Standardize database naming and fix environment configuration

- Renamed database from 'decision_tree' to 'apoklisis' for consistency
- Updated docker-compose.yml: container renamed to 'apoklisis_postgres'
- Updated .env file with correct database URL
- Verified backend authentication flow working correctly
- Added postgres MCP server to Claude Code configuration

backend/.claude/settings.local.json

@@ -0,0 +1,7 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(test:*)"
+    ]
+  }
+}

backend/docker-compose.yml

@@ -1,13 +1,11 @@
-version: '3.8'
-
 services:
   db:
     image: postgres:16-alpine
-    container_name: decision_tree_db
+    container_name: apoklisis_postgres
     environment:
       POSTGRES_USER: postgres
       POSTGRES_PASSWORD: postgres
-      POSTGRES_DB: decision_tree
+      POSTGRES_DB: apoklisis
     ports:
       - "5432:5432"
     volumes: