feat(openclaw): add runtime closure meta-package for Harmonia caching

Creates openclaw-runtime-closure as a symlinkJoin of all runtime dependencies (nodejs_22, kubectl, jq, git, emacs, tsx, tea, python3.withPackages pymupdf, qmd) that will be pushed to the Harmonia binary cache by CI and pulled into the PVC by the init container at pod startup.

This meta-package enables the thin Docker image architecture where:
- The Docker image stays small (~1.5GB vs 2.7GB) with only /app, nix, and basics
- Runtime deps are fetched from Harmonia at pod startup via nix copy --from
- CI push is fast (thin image) and runtime deps are cached separately

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

packages/openclaw-image/runtime-closure.nix

@@ -0,0 +1,22 @@
+{
+  pkgs,
+  qmd,
+}:
+
+# This package creates a store path that transitively depends on all packages
+# that should be available at runtime in the OpenClaw pod.
+# CI uses this to push a single closure to Harmonia.
+pkgs.symlinkJoin {
+  name = "openclaw-runtime-closure";
+  paths = [
+    pkgs.nodejs_22
+    pkgs.kubectl
+    pkgs.jq
+    pkgs.git
+    pkgs.emacs
+    pkgs.tsx
+    pkgs.tea
+    (pkgs.python3.withPackages (ps: [ ps.pymupdf ]))
+    qmd
+  ];
+}