feat(vscode-web): enhance settings management and testing for VS Code Web

[DevelopmentCats]

This pull request enhances the VS Code Web module by improving how machine settings are handled and merged, updating documentation to clarify the settings behavior, and adding robust automated tests for the new functionality. The most significant changes are grouped below.

Machine Settings Handling and Merging:

• Introduced a new merge_settings function in run.sh that merges provided settings with any existing machine settings using jq or python3 if available, falling back gracefully if neither is present. Settings are now passed as base64-encoded JSON to avoid quoting issues. [1] [2] [3] [4]
• Updated the settings variable in main.tf to clarify that it applies to VS Code Web's Machine settings and will be merged with any existing settings on startup.

Documentation Improvements:

• Updated the README to clarify that settings are merged with existing machine settings, not simply overwritten, and added a note about the requirements (jq or python3) and limitations regarding persistence of user settings. [1] [2]

Automated Testing:

• Expanded main.test.ts to include integration tests that verify settings file creation and merging behavior inside a container, as well as improved error handling for invalid configuration combinations.

These changes collectively make machine settings management more robust, user-friendly, and well-documented.

[Copilot]

Pull request overview

This PR improves VS Code Web module “Machine settings” handling by merging module-provided settings into an existing VS Code settings file on startup, clarifies the behavior in Terraform docs/README, and expands the module’s automated tests around configuration validation and settings behavior.

Changes:

• Add a merge_settings helper to merge decoded settings JSON into ~/.vscode-server/data/Machine/settings.json, preferring jq and falling back to python3.
• Pass settings to the startup script as base64-encoded JSON (SETTINGS_B64) to avoid quoting issues.
• Expand main.test.ts with container-based tests for settings file creation/merge and improve apply-failure assertions.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
registry/coder/modules/vscode-web/run.sh	Adds machine settings merge logic and decodes settings from base64 before applying.
registry/coder/modules/vscode-web/main.tf	Documents machine-settings semantics and switches settings injection to base64 JSON via locals.
registry/coder/modules/vscode-web/main.test.ts	Adds integration tests for settings creation/merge and updates failure assertions.
registry/coder/modules/vscode-web/README.md	Clarifies “Machine settings” behavior, merge semantics, and tool requirements.

[DevelopmentCats]

@matifali What do you think we need to do in regards to version bump on this one?

Technically I feel like its fine as a patch, but since its not just a simple change and this requires additional dependencies for settings merging I think it might be fine as a minor bump?

[matifali]

@DevelopmentCats Minor is good here. It's a change in behaviour.

[github-actions]

Version Bump Required

One or more modules in this PR need their versions updated.

To fix this:

1. Run the version bump script locally:

   ./.github/scripts/version-bump.sh minor

2. Commit the changes:

   git add . && git commit -m "chore: bump module versions (minor)"

3. Push your changes

The CI will automatically re-run once you push the updated versions.

[matifali]

LGTM. Do we have a similar setup for code-server module too? If not let's do it