Initial commit — encrypted chat server + Python clients (v0.8.5)

E2E encrypted chat (X3DH + Double Ratchet, Signal Protocol).
Server: asyncio TCP + TLS, MySQL. Clients: PyQt6 GUI + CLI.
Secrets (.env, TLS keys, Cloudflare token), runtime data and
mobile clients (separate repos) are gitignored.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,70 @@
+version: "3.9"
+
+# Local development stack: encrypted-chat server + MySQL
+# Usage:
+#   docker compose up          — start server + db
+#   docker compose up --build  — rebuild server image first
+#   docker compose down -v     — stop and remove volumes (wipes DB data)
+
+services:
+  db:
+    image: mysql:8.0
+    restart: unless-stopped
+    environment:
+      MYSQL_ROOT_PASSWORD: devpassword
+      MYSQL_DATABASE: encrypted_chat
+      MYSQL_USER: chat
+      MYSQL_PASSWORD: chatpassword
+    volumes:
+      # Persist DB data between restarts
+      - db_data:/var/lib/mysql
+      # Auto-import schema on first start
+      - ./schema.sql:/docker-entrypoint-initdb.d/01_schema.sql:ro
+    ports:
+      - "3306:3306"
+    healthcheck:
+      test: ["CMD", "mysqladmin", "ping", "-h", "localhost", "-u", "root", "-pdevpassword"]
+      interval: 10s
+      timeout: 5s
+      retries: 10
+      start_period: 30s
+
+  server:
+    build: .
+    restart: unless-stopped
+    depends_on:
+      db:
+        condition: service_healthy
+    ports:
+      - "5000:5000"
+    volumes:
+      - uploads:/app/uploads
+    environment:
+      # MySQL connection
+      MYSQL_HOST: db
+      MYSQL_PORT: 3306
+      MYSQL_USER: chat
+      MYSQL_PASSWORD: chatpassword
+      MYSQL_DATABASE: encrypted_chat
+      DB_POOL_SIZE: 10
+
+      # Server config
+      SERVER_HOST: 0.0.0.0
+      SERVER_PORT: 5000
+      UPLOAD_DIR: /app/uploads
+
+      # Dev mode: registration codes returned in response (no SMTP needed)
+      ENVIRONMENT: dev
+
+      # TLS: disabled by default for local dev (set TLS_ENABLED=true for prod)
+      TLS_ENABLED: "false"
+
+      # Logging
+      LOG_LEVEL: INFO
+
+      # Metadata retention (days)
+      METADATA_RETENTION_DAYS: 90
+
+volumes:
+  db_data:
+  uploads: