[yansawu]

User currently have to select their submitted code manually to copy it from the final report. Add a Copy code button beside Your final code, preserve the original whitespace and line breaks, and show brief success or error feedback.

Hide the button when code is unavailable, including reports containing the unsaved-code placeholder. Code persistence remains unchanged.

Automated tests cover successful copying, clipboard errors, unavailable code, and repeated clicks while copying.

Closes #318

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Summary by cubic

Adds a Copy code button next to "Your final code" in the report so candidates no longer have to select their submission manually. The button copies the original submission text, preserving whitespace and line breaks, and shows "Copied!" feedback or an error message when clipboard access fails.

• Shows a "Copying..." state and a disabled appearance while a copy is pending, and ignores duplicate clicks.
• Hides the button when code is unavailable, including reports with the unsaved-code placeholder. Code persistence is unchanged.

^{Written for commit fc8b143. Summary will update on new commits.}

[jserv]

The button's visibility depends on matching the literal "(final code was not saved)", which is also hard-coded in the Past attempts card (web/app.js, which calls reportMarkup with that string and never calls mountFinalCodeCopy) and in reportMarkdown. If any of those copies changes its wording, Past attempts shows a "Copy code" button with no handler, so clicking it does nothing. Export one constant from render.js and use it in all three places (or have app.js pass code: null and treat null as not saved here).

[jserv]

Add screenshots to the pull request description to illustrate your work, as @ColtenOuO suggests. Example: #349

[jserv]

This stub hands back status for any selector other than [data-copy-code], and every test mounts on the stub rather than on what reportMarkup emits, so nothing ties data-copy-code-status in the markup to the selector mountFinalCodeCopy queries. If the two drift, status is null, the click throws at status.textContent before the try, and the button stays aria-disabled for good while every test here still passes. Mount at least one test on the real reportMarkup output (for example parse it with the DOM the other browser tests use) and assert the status text changes there.