Auto-detect esbuild for v13+ branches

[goransle]

Summary

Automatically detect and enable esbuild mode for Highcharts v13+ branches by checking for the presence of ts/masters/highcharts-autoload.src.ts on the branch.

Changes

• Added branchNeedsEsbuild() function that performs a GitHub HEAD request to detect v13+ branches
• Fixed bug where single-segment branch names weren't stripped from URLs when resolved to commit SHA
• Anchored URL .replace() calls to path segment boundaries to prevent filename corruption
• Refactored response handling into respondToClient for consistency
• Updated @highcharts/highcharts-utils dependency
• Added comprehensive test coverage

[Copilot]

Pull request overview

This PR adds automatic esbuild enablement for newer Highcharts branches (v13+) by probing the branch for the presence of ts/masters/highcharts-autoload.src.ts, and updates tests/docs to reflect the new behavior.

Changes:

• Add branchNeedsEsbuild() detection (GitHub HEAD request) and auto-enable esbuild in handlerDefault when appropriate.
• Tighten URL SHA-rewrite logic to replace only full path segments (avoid filename corruption) and fix single-segment branch rewrite behavior.
• Add/adjust unit + Hurl integration tests and update documentation; bump @highcharts/highcharts-utils.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
app/handlers.js	Adds esbuild auto-detection + caching and updates URL rewriting before serving/building.
README.md	Documents automatic esbuild behavior for v13+ and how to verify via headers.
test/esbuild.js	Extends unit coverage for autoload + data-sorting paths/configs.
test/hurl/smoke.hurl	Adds basic local smoke check.
test/hurl/esbuild-autoload.hurl	Adds integration checks for esbuild compilation + auto-detection.
test/hurl/dashboards.hurl	Adds integration checks for dashboards endpoints.
test.hurl	Points users to the new test/hurl/*.hurl layout.
package.json	Pins @highcharts/highcharts-utils to a GitHub branch.
package-lock.json	Updates lockfile for dependency changes.

[Copilot]

esbuildCache is an unbounded Map and will grow indefinitely with unique refs/SHAs, which can become a long-lived memory leak in a server process. Consider switching to a bounded LRU/TTL cache (e.g., cap entries and/or expire after N minutes), or only caching for known branch names (not every commit SHA).

[Copilot]

Pinning @highcharts/highcharts-utils to a moving branch (#fix/uniquekey-compile-on-demand) makes installs non-reproducible and can unexpectedly change behavior over time. Consider pinning to a specific commit SHA or a tagged release, and documenting why this fork/branch is required.

Suggested change

	"@highcharts/highcharts-utils": "github:highcharts/highcharts-utils#fix/uniquekey-compile-on-demand",
	"@highcharts/highcharts-utils": "github:highcharts/highcharts-utils#<full-commit-sha-for-the-required-fix>",