release: 2.10.4: origin-strict - a change with neither header is refused

Cut without asking, as the owner said on 2026-10-15. A POST with neither
Sec-Fetch-Site nor Origin is refused (the commit before this); the e2e
client sends Origin. go vet, go test (26 packages) and make e2e passed on
the test server for that tree. No migration, schema 12.

CHANGELOG [2.10.4]; pins in deploy/docker-compose.yml, README and the guide
(pin, build, the sample restore message); development's "from pin" and
row 36; roadmap row. No tag.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/development.md

@@ -107,7 +107,7 @@ than the default «meaningful step» rule in [§ Commits and release build](#com
 2. Git tag `vX.Y.Z` and publish the GitHub Release only on explicit request (see
    [§ Release image](#release-image)).
 
-**Planned version cuts** (from pin `2.10.3`; adjust if semver changes mid-track):
+**Planned version cuts** (from pin `2.10.4`; adjust if semver changes mid-track):
 
 | Stage | ID | Cut |
 |---|---|---|
@@ -146,6 +146,7 @@ than the default «meaningful step» rule in [§ Commits and release build](#com
 | 33 | long, non-repeating queue ids | `2.10.1` (PATCH) |
 | 34 | phone-desktop-mode | `2.10.2` (PATCH) |
 | 35 | backup-reauth | `2.10.3` (PATCH) |
+| 36 | origin-strict | `2.10.4` (PATCH) |
 
 Docs-only prep (checklists in plans, no product code) uses the same per-step
 commit rule but **no** version cut until the next product stage ships.