lmcp: Debian packaging + CI publish via hertz reprepro

- debian/lmcp/build-deb.sh fetches the v0.3.0 tarball, lays out the
  filetree, and uses dpkg-deb to assemble lmcp_0.3.0-1_all.deb directly
  on the Arch aarch64 runner (no debhelper needed for a pure-Lua pkg).
- workflow job 'lmcp-debian' rsyncs the .deb to hertz's marfritrepo
  incoming dir, then ssh-triggers 'publish-deb <suite>' for both
  bookworm and trixie. publish-deb wraps 'reprepro includedeb' and
  rsyncs dists/+pool/ to nc.
- New secret MARFRIT_REPO_HERTZ_KEY uploaded to Gitea repo. Forced
  command on hertz routes rsync uploads vs publish-deb triggers.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

debian/lmcp/debian/control

@@ -0,0 +1,17 @@
+Source: lmcp
+Section: net
+Priority: optional
+Maintainer: Markus Fritsche <mfritsche@reauktion.de>
+Build-Depends: debhelper-compat (= 13)
+Standards-Version: 4.6.2
+Homepage: https://git.reauktion.de/marfrit/lmcp
+
+Package: lmcp
+Architecture: all
+Depends: ${misc:Depends}, lua5.4 | lua5.3 | lua, lua-socket
+Description: Lightweight MCP (Model Context Protocol) server in pure Lua
+ lmcp is a small Model Context Protocol server written in Lua. It exposes
+ user-defined tools over HTTP for use by AI agents.
+ .
+ Library files install to /usr/share/lua/5.4/. The example server is
+ available as /usr/bin/lmcp-example.