feat: pi-devbox parity — typst PDF, terminal terminfo, nvim colour, host-ssh check, hygiene

Ports the base additions from pi-devbox v1.4.0 + v1.5.0 that opencode-devbox
lacked (opencode-devbox already tracks pi-devbox for CLI-toolset parity, v2.6.0):

- typst PDF engine for pandoc (v1.4.0) + the pandoc typst-template default-font
  patch (v1.5.0) so 'pandoc --pdf-engine=typst' works without -V mainfont.
  pandoc shipped since v2.6.0 as a front-end only (no PDF back-end). +xz-utils.
  Tracks latest; --build-arg TYPST_VERSION escape hatch.
- Terminal support (v1.5.0): ncurses-term + kitty-terminfo + a compiled
  xterm-ghostty alias (tic -x, use=ghostty), so wezterm/alacritty/foot/ghostty/
  kitty resolve TERM over SSH instead of degrading to a dumb fallback.
- Readable Neovim colours (v1.5.0): system-wide /etc/xdg/nvim/sysinit.vim with
  termguicolors.
- Host SSH reachability check at shell startup (v1.4.0): one-time probe in
  .bash_aliases warning (with fix steps + inline pubkey) when the Mac host is
  unreachable. The rest of the LAN stack was already present.
- .claude/settings.local.json added to the gitignore_global seed (v1.5.0).
- Repo hygiene (v1.5.0): LICENSE (MIT), THIRD_PARTY.md, hadolint CI job (pinned
  v2.14.0) + .hadolint.yaml, IDEAS.md backlog.

Base-affecting (Dockerfile.base + rootfs) → base-<hash> advances, base rebuilds.
smoke-test gains typst/PDF, terminfo, and nvim-tgc assertions. Validated:
hadolint clean on both Dockerfiles, bash -n OK, base-hash guard OK, workflow
guard OK. CHANGELOG v2.7.0.

scripts/smoke-test.sh

@@ -8,6 +8,10 @@
 #   - Entrypoint runs cleanly as non-root after UID adjustment
 #   - Generated opencode.json has the expected shape
 #   - MCP wrapper works (when mempalace is installed)
+#   - typst PDF engine for pandoc — `pandoc --pdf-engine=typst`
+#   - terminfo for modern emulators: xterm-kitty, xterm-ghostty, wezterm,
+#     alacritty, foot (kitty-terminfo + ncurses-term + compiled ghostty alias)
+#   - Neovim true-colour default (sysinit.vim termguicolors)
 #
 # Usage: ./scripts/smoke-test.sh <image> [--variant base|omos]
 #
@@ -119,6 +123,10 @@ run "node"              "node --version"
 run "npm"               "npm --version"
 run "git"               "git --version"
 run "nvim"              "nvim --version | head -1"
+run "nvim true-colour default (sysinit.vim)" "nvim --headless -c 'lua os.exit(vim.o.termguicolors and 0 or 1)'"
+run "kitty-terminfo"    "infocmp -x xterm-kitty >/dev/null 2>&1"
+run "terminfo: modern emulators (ncurses-term)" 'for t in wezterm alacritty foot ghostty st-256color; do infocmp -x "$t" >/dev/null 2>&1 || exit 1; done'
+run "terminfo: xterm-ghostty alias (tic)" "infocmp -x xterm-ghostty >/dev/null 2>&1"
 run "nano"              "nano --version | head -1"
 run "micro"             "micro --version"
 run "bat"               "bat --version"
@@ -139,6 +147,8 @@ run "gitea-mcp"         "gitea-mcp --version"
 run "gosu"              "gosu --version"
 run "tmux"              "tmux -V"
 run "pandoc"            "pandoc --version | head -1"
+run "typst"             "typst --version"
+run "pandoc+typst PDF engine" "printf '# hi\n' | pandoc --pdf-engine=typst -o /tmp/_smoke.pdf - && test -s /tmp/_smoke.pdf; rm -f /tmp/_smoke.pdf"
 run "graphviz (dot)"    "dot -V"
 run "tldr (tealdeer)"   "tldr --version"
 run "dot-watch"         "test -x /usr/local/bin/dot-watch && bash -n /usr/local/bin/dot-watch && echo ok"