Initial commit: email-openclaw bridge v1

Full pipeline: IMAP ingress -> OpenClaw dispatch -> callback -> SMTP reply.
SQLite stateful storage with idempotency, threading, and retry logic.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.env.example

@@ -0,0 +1,24 @@
+# === IMAP ===
+IMAP_HOST=imap.example.com
+IMAP_PORT=993
+IMAP_USER=bridge@example.com
+IMAP_PASS=changeme
+
+# === SMTP ===
+SMTP_HOST=smtp.example.com
+SMTP_PORT=587
+SMTP_USER=bridge@example.com
+SMTP_PASS=changeme
+
+# === OpenClaw ===
+OPENCLAW_URL=https://api.openclaw.example.com
+OPENCLAW_API_KEY=
+
+# === Bridge ===
+BRIDGE_CALLBACK_TOKEN=a-strong-random-token
+SYSTEM_EMAIL=bridge@example.com
+WHITELIST_EMAILS=user1@example.com,user2@example.com
+
+# === Optional ===
+IMAP_PROXY_URL=
+LISTEN_ADDR=:8080