release: 1.1.0

Close the [Unreleased] section as 1.1.0 and move the deploy pin, the README
trial command, and the guide's stated pin to that tag.

Corrections to the section while cutting it:

- The GHCR "unknown blob" retry was filed under Unreleased, but the commit
  carrying it is what v1.0.0 points at. Moved into the 1.0.0 section.
- docs/plans/ and the roadmap's restructure into a 1.x+ tracker were missing
  entirely; the plans were described only as "translated", which reads as if
  they predated this release. Filed under Added.
- docs/product.md's reframing of the future line -- agreed 1.x+ extensions,
  inbound relay targeting a MINOR by default, approval needed only for
  candidates -- was unrecorded.
- The Account/Settings rename also touched the operator guide.

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

deploy/docker-compose.yml

@@ -22,7 +22,7 @@
 
 services:
   selfpost:
-    image: ghcr.io/mixeme/selfpost:1.0.0
+    image: ghcr.io/mixeme/selfpost:1.1.0
     restart: unless-stopped
     environment:
       SELFPOST_HOSTNAME: "${SELFPOST_HOSTNAME:?set the mail/panel hostname, e.g. mail.example.com}"