Add worktree switching support

[goransle]

• Add lib/worktree.js for git worktree discovery
• Add dynamic getters (getHighchartsDir/getSamplesDir/getApiDir) to lib/arguments.js
• Add /api/worktree endpoints (routes/worktree.js)
• Refactor all static highchartsDir/samplesDir imports to use dynamic getters
• Add worktree dropdown to nav bar with 🌲 label
• Reinitialize file watchers on worktree switch
• Add path containment security check

Test plan

• create two branch worktrees in the highcharts repo

  git worktree add ../highcharts-worktrees/wt-master master
  git worktree add ../highcharts-worktrees/wt-feature -b test/worktree-switch

• Locate the worktree dropdown. Ensure there's now worktrees available (including the existing repo)
• Make a change to a sample or code in one of the worktrees and ensure it's reflected when changing worktree via the dropdown

[Copilot]

Pull request overview

Adds git worktree awareness to highcharts-utils so the running app can switch between multiple Highcharts checkouts without a server restart, including a UI selector, API endpoints, and dynamic path resolution across routes/watchers.

Changes:

• Introduces worktree discovery (lib/worktree.js) plus /api/worktree endpoints to list/select active worktrees.
• Refactors path usage to dynamic getters (getHighchartsDir / getSamplesDir / getApiDir) so routes/static serving follow the selected worktree.
• Updates the UI (nav dropdown) and watcher logic to reinitialize file watching after switching worktrees; adds a Playwright-based script for scanning sample console errors.

Reviewed changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
views/samples/contents.hbs	Minor template cleanup (whitespace/blank line).
views/partials/nav.hbs	Adds worktree selector UI in the top bar next to version display.
server.js	Uses dynamic Highcharts dir getter for logging and package.json resolution.
scripts/check-samples-console.mjs	New script to crawl sample pages and report console/page errors via Playwright.
routes/worktree.js	New API routes for listing worktrees and persisting selected worktree to config.
routes/samples/view.js	Switches sample file operations to use getHighchartsDir() dynamically.
routes/samples/share.js	Switches sample asset reads to use getHighchartsDir() dynamically.
routes/samples/list-samples.js	Switches sample discovery to use getSamplesDir() dynamically.
routes/samples/edit.js	Switches editor file reads to use getSamplesDir() dynamically.
routes/samples/data.js	Serves sample data files from getSamplesDir() dynamically.
routes/samples/contents.js	Passes dynamic highchartsDir to template.
routes/samples/compare-view.js	Passes dynamic highchartsDir to template.
routes/bisect/commits.js	Refactors to use dynamic Highcharts dir for git operations.
routes/bisect/bisect.js	Updates git spawn working directory to dynamic Highcharts dir.
public/stylesheets/style.less	Adds layout/styles for the worktree selector in the top bar.
public/javascripts/nav.js	Fetches worktrees and posts selection to reload app on switch.
lib/worktree.test.js	Adds unit tests for parsing git worktree list --porcelain -z.
lib/worktree.js	Implements git worktree discovery/parsing and validity marking.
lib/websocket.js	Refactors watcher initialization to support reinit on worktree switch.
lib/functions.js	Replaces static dirs with dynamic getters across sample-related helpers.
lib/compile-on-demand.js	Uses dynamic Highcharts dir for resolving package/master paths.
lib/arguments.js	Adds dynamic getters and a containment check for selected worktree paths.
app.js	Serves worktree-dependent static dirs and registers /api/worktree.
app-api.js	Serves API docs from dynamically selected worktree’s build output.

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[MarkusBarstad]

Works!

Messed with my head a bit that you have to npx gulp in each worktree to serve files 😆