Version cut 1.9.3: close the panel-redesign docs prep, bump the pin

CHANGELOG.md audited against the full commit history from the repo's
first commit (8ad56ed) through HEAD: version/date headings, entry
completeness, and technical claims against their diffs all check out,
no discrepancies found.

The Unreleased section (panel-redesign mockups, contract, and
decisions; preflight plan) is docs-only prep — development.md's own
rule would hold the cut until a product stage ships — but the owner
asked for a version cut now, so it becomes 1.9.3 (PATCH) and a fresh
Unreleased opens. Pin bumped in deploy/docker-compose.yml, README's
quickstart, guide.md, and development.md's planned-cuts table, which
also gains the new row (renumbering inbound-antispam-panel to 11).

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

CHANGELOG.md

@@ -5,6 +5,14 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); version
 
 ## [Unreleased]
 
+## [1.9.3] - 2026-09-22
+
+Panel-redesign prep, docs only: stage 1-2 mockups on all 33 screens, the
+accepted header/type-scale/contrast corrections, the account e-mail and
+inbound-delegation decisions, and the routes/quarantine/preflight roadmap
+screens. Nothing in `internal/web` changes; the design stays `candidate`
+(3/21) until the redesign itself ships as `2.0.0`.
+
 ### Added
 
 - Panel redesign, account e-mail and notifications: a user's e-mail is its own