refactor(openclaw): thin Docker image with Nix deps offloaded to Harmonia

Strips runtime packages (nodejs_22, kubectl, jq, git, emacs, tsx, tea, pythonEnv, qmd) from the Docker image contents, reducing image size from ~2.7GB to ~1.5GB.

Key changes:
- Removed 9 runtime packages from contents (moved to openclaw-runtime-closure)
- Removed pythonEnv let binding and qmd parameter (no longer needed in image)
- Added OPENCLAW_RUNTIME_CLOSURE env var (bakes closure path for init container)
- Added runtime closure bin dir to PATH (resolves after PVC population)
- Added curl to contents (needed by init container for Harmonia health checks)
- CI: added openclaw-runtime-closure to build-and-cache PACKAGES array
- CI: added second sed command for CronJob image tag update
- CI: removed inherit qmd from openclaw-image callPackage (qmd now in runtime closure)

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

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

packages/default.nix

@@ -9,6 +9,6 @@ rec {
   nextcloud-talk-desktop = pkgs.callPackage ./nextcloud-talk-desktop { };
   opencode = pkgs.callPackage ./opencode { };
   qmd = pkgs.callPackage ./qmd { };
-  openclaw-image = pkgs.callPackage ./openclaw-image { inherit qmd; };
+  openclaw-image = pkgs.callPackage ./openclaw-image { };
   openclaw-runtime-closure = pkgs.callPackage ./openclaw-image/runtime-closure.nix { inherit qmd; };
 }