ci: validate WPCodeSpace OpenVSCode image build

[tariqsaidofficial]

Summary

Adds validation-first CI for building and smoke testing a WPCodeSpace OpenVSCode test image.

What this validates

The workflow:

• installs Linux native build dependencies
• runs npm ci
• prepares out-build/date
• builds the proven web server output with npm run gulp vscode-reh-web-linux-x64-min-ci
• validates ../vscode-reh-web-linux-x64 exists
• validates bin/openvscode-server and node are executable
• creates a Docker build context from the proven server output
• builds a local test image
• starts the container
• curls the local OpenVSCode HTTP endpoint
• confirms no tracked generated workbench.js or nls.messages patching is required

Scope

CI validation only.

No image publishing.

No GHCR push.

No source changes.

No WPCodeSpace consumption changes.

No generated runtime files committed.

Next phase after this passes

Use the validated image build path to define GHCR publishing with immutable commit SHA tags, then run the image locally and visually verify the official Chat panel copy before WPCodeSpace consumes the image.