feat: DevDesk v0.1.0, a persistent browser terminal for Claude Code

ttyd serves a single-file xterm.js UI styled with the LotusGuild TDS
(web_template base.css). Sessions live in a dedicated tmux server unit
(devdesk-tmux.service), so restarting or upgrading the web unit never
stops Claude. Each named session maps to a project directory. A Claude
SessionStart hook records the conversation ID, so after a reboot the
session resumes that exact conversation.

- bin/devdesk: attach / new / ls / end / pick, with an fzf picker
- ttyd requires a credential that NPM injects; origin check enabled
- debian/: dh 13 with --no-stop-on-upgrade for the tmux unit, bundled
  sha256-verified ttyd 1.7.7, lintian overrides, man page
- CI: lint, test, build, smoke-test, artifact; v* tags publish to the
  Gitea apt registry and create a release

Refs: tinker ticket 887531976

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

debian/devdesk.postinst

@@ -0,0 +1,22 @@
+#!/bin/sh
+set -e
+
+case "$1" in
+configure)
+    # Credential ttyd requires; NPM injects it as an Authorization header.
+    if [ ! -s /etc/devdesk/secret.env ]; then
+        umask 077
+        secret=$(od -An -tx1 -N24 /dev/urandom | tr -d ' \n')
+        printf 'DEVDESK_CREDENTIAL=devdesk:%s\n' "$secret" >/etc/devdesk/secret.env
+    fi
+    chmod 600 /etc/devdesk/secret.env
+    # Apply tmux.conf changes to a running server without restarting it.
+    if [ -S /run/devdesk/tmux.sock ]; then
+        tmux -N -S /run/devdesk/tmux.sock source-file /usr/share/devdesk/tmux.conf >/dev/null 2>&1 || true
+    fi
+    ;;
+esac
+
+#DEBHELPER#
+
+exit 0