refactor(coolify): externalize postgres, qdrant, S3

- Replace bp-core-postgres with POSTGRES_HOST env var
- Replace bp-core-qdrant with QDRANT_URL env var
- Replace bp-core-minio with S3_ENDPOINT/S3_ACCESS_KEY/S3_SECRET_KEY

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

.env.coolify.example

@@ -5,7 +5,9 @@
 # for the breakpilot-lehrer Docker Compose resource.
 # =========================================================
 
-# --- Database (shared with Core) ---
+# --- External PostgreSQL (Coolify-managed, same as Core) ---
+POSTGRES_HOST=<coolify-postgres-hostname>
+POSTGRES_PORT=5432
 POSTGRES_USER=breakpilot
 POSTGRES_PASSWORD=CHANGE_ME_SAME_AS_CORE
 POSTGRES_DB=breakpilot_db
@@ -13,10 +15,15 @@ POSTGRES_DB=breakpilot_db
 # --- Security ---
 JWT_SECRET=CHANGE_ME_SAME_AS_CORE
 
-# --- MinIO (from Core) ---
-MINIO_ROOT_USER=breakpilot
-MINIO_ROOT_PASSWORD=CHANGE_ME_SAME_AS_CORE
-MINIO_BUCKET=breakpilot-rag
+# --- External S3 Storage (same as Core) ---
+S3_ENDPOINT=<s3-endpoint-host:port>
+S3_ACCESS_KEY=CHANGE_ME_SAME_AS_CORE
+S3_SECRET_KEY=CHANGE_ME_SAME_AS_CORE
+S3_BUCKET=breakpilot-rag
+S3_SECURE=true
+
+# --- External Qdrant (Coolify-managed, same as Core) ---
+QDRANT_URL=http://<coolify-qdrant-hostname>:6333
 
 # --- Session ---
 SESSION_TTL_HOURS=24