feat: add yq, pandoc, graphviz, tldr (tealdeer) + dot-watch — CLI parity with pi-devbox

- apt: yq (YAML query), pandoc (doc converter), graphviz (dot rendering)
- tealdeer: tldr command as ~5MB static musl binary (TEALDEER_VERSION arg)
- dot-watch: auto-render .dot to PNG on save (graphviz-only, no imagemagick)
- README: document new tools
- smoke-test: presence assertions for yq, pandoc, dot, tldr, dot-watch

Excludes socat, imagemagick, studio-expose (pi-studio-specific).

scripts/smoke-test.sh

@@ -131,12 +131,17 @@ run "fzf"               "fzf --version"
 run "fd"                "fd --version"
 run "rg"                "rg --version | head -1"
 run "jq"                "jq --version"
+run "yq"                "yq --version"
 run "git-crypt"         "git-crypt --version | head -1"
 run "gitleaks"          "gitleaks version"
 run "aws"               "aws --version"
 run "gitea-mcp"         "gitea-mcp --version"
 run "gosu"              "gosu --version"
 run "tmux"              "tmux -V"
+run "pandoc"            "pandoc --version | head -1"
+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"
 
 # SSH ControlMaster baked defaults: the config file must exist (image-level)
 # and ssh -G must report ControlPath rooted at /tmp/sshcm/ for an arbitrary