Initial commit: thbd-portal, duplicated from elmi-portal

Rebranded for Thunderbird Portal (THBD): numbering prefix EL->TH, all
"ELMI"/"ЭЛМИ" UI strings genericized, ELMI's real contract templates and
company legal/bank details removed (not applicable to this company), fresh
VAPID keypair and encryption key, fresh single-migration schema history.
Same architecture as elmi-portal: Web Push notifications, unread-chat app
badge, cookie-session auth.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gh2UXUQUVBWroWEnn1FLFG

docker-compose.yml

@@ -0,0 +1,16 @@
+services:
+  app:
+    build: .
+    ports:
+      - "8088:8088"
+    env_file:
+      - .env
+    environment:
+      - PORT=8088
+      - DATA_DIR=/data
+    volumes:
+      - data:/data
+    restart: unless-stopped
+
+volumes:
+  data: