feat(deploy): docker image, caddy, compose, e2e script

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMHQTtnQtQqL8muAXHr9kd

scripts/docker-compose.e2e.yml

@@ -0,0 +1,21 @@
+# Override used only by scripts/e2e.sh: adds a greenmail IMAP server that
+# acts as BOTH the source and the destination (two mailboxes, one server),
+# reachable from the app container via compose DNS as host "greenmail".
+services:
+  greenmail:
+    image: greenmail/standalone:latest
+    environment:
+      GREENMAIL_OPTS: >-
+        -Dgreenmail.setup.test.all
+        -Dgreenmail.hostname=0.0.0.0
+        -Dgreenmail.auth.disabled
+        -Dgreenmail.verbose
+    ports:
+      # exposed to the host so the seeding script (running outside docker)
+      # can APPEND test messages into the source mailbox
+      - "3143:3143"
+
+  app:
+    depends_on:
+      greenmail:
+        condition: service_started