The way back in: replies read over JMAP, handed to portal as notes

A mail about a record now answers to case+<bucket>.<record>@<domain>
when a mailbox is configured, and gdo reads that mailbox: it cuts the
quoted history off what the person wrote, publishes each reply on
portal.mail.received, and marks it seen only once portal has it. The
address carries portal's own chain hash and opens nothing by itself;
portal checks the sender against the record and never moves a case on
a reply. Unconfigured, gdo sends exactly as before.

Tested: the address built for a case and refused for an invite, the
address parsed back or rejected (wrong domain, wrong prefix, no
record, odd characters), the quote and signature cut in English and
Norwegian, a JMAP mail turned into a reply with its own id, an
HTML-only mail falling back to its preview, and a half-configured
mailbox staying off.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 0.2.0 (2026-09-24)
+
+- The way back in: with a mailbox configured (`JMAP_URL`, `JMAP_TOKEN`, `MAIL_REPLY_DOMAIN`), every mail about a record carries a Reply-To of its own, `case+<bucket>.<record>@<domain>`, and replies to it are read over JMAP and published on `portal.mail.received` for portal to append as notes. The record id in the address is portal's own unguessable chain hash, and portal checks the sender against the address the record holds, so the address alone opens nothing.
+- A reply is read for what the person wrote: the quoted history, the signature and the attribution line are cut off, and an HTML-only mail falls back to its preview. Nothing is marked seen until portal has it.
+- Unconfigured, gdo sends exactly as before and never reads anything.
+
 ## 0.1.2 (2026-09-23)
 
 - The stream is `mail`, not shouted; matches portal 0.3.44. The unit runs the packaged binary at /usr/bin/gdo.