Initial commit: webmail client (M0/M1)

Three-pane webmail client.
- Backend: FastAPI + async SQLAlchemy + arq worker (Postgres/Redis), IMAP/SMTP
  sync, threading, search, drafts/outbox with undo, attachments, 2FA.
- Frontend: React 18 + Vite + TypeScript + TanStack Query + Tailwind; three-pane
  UI with rich-text composer, light/dark themes, resizable panels.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker/docker-compose.yml

@@ -0,0 +1,53 @@
+name: webmail
+services:
+  postgres:
+    image: postgres:16
+    environment:
+      POSTGRES_USER: webmail
+      POSTGRES_PASSWORD: webmail_dev
+      POSTGRES_DB: webmail_dev
+    ports: ["127.0.0.1:5433:5432"]
+    volumes: [pgdata:/var/lib/postgresql/data]
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U webmail -d webmail_dev"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+
+  redis:
+    image: redis:7
+    ports: ["127.0.0.1:6380:6379"]
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+
+  meilisearch:
+    image: getmeili/meilisearch:v1.8
+    environment:
+      MEILI_MASTER_KEY: dev_master_key_change_me
+      MEILI_ENV: development
+    ports: ["127.0.0.1:7700:7700"]
+    volumes: [meilidata:/meili_data]
+    healthcheck:
+      test: ["CMD-SHELL", "wget -qO- http://127.0.0.1:7700/health | grep -q available"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+
+  # Test mail servers (integration tests + manual dev against a throwaway mailbox)
+  greenmail:
+    image: greenmail/standalone:2.0.1
+    environment:
+      GREENMAIL_OPTS: >-
+        -Dgreenmail.setup.test.all -Dgreenmail.hostname=0.0.0.0
+        -Dgreenmail.users=dev:devpass@dev.local -Dgreenmail.verbose
+    ports:
+      - "127.0.0.1:3025:3025"   # SMTP
+      - "127.0.0.1:3143:3143"   # IMAP
+      - "127.0.0.1:3993:3993"   # IMAPS
+
+volumes:
+  pgdata:
+  meilidata: