chore(ggplot2): follow-up Copilot review fixes after #6944 merge

[MarkusNeusinger]

Summary

Three Copilot review comments arrived on #6944 just before/after it was merged. Picking up the actionable ones in a small follow-up.

What's fixed

1. PlotOfTheDayTerminal — hardcoded python prompt (#discussion_r3253434308)
The terminal-style chip in the POTD card had a hardcoded python label even though the filename now flips to .R for ggplot2. Output would read python plots/<spec>/ggplot2.R — wrong. Now derives a runner token from potd.language (Rscript for r, python otherwise) alongside the existing ext switch.

2. prompts/plot-generator.md — contradictory docstring rule (#discussion_r3253434312)
The "Forbidden (Python)" list said "Type hints or docstrings (keep it simple)" while the same prompt elsewhere requires a 4-line module-header docstring at the top of every Python impl. Contradictory guidance can make generators omit the required header. Clarified: header docstring is mandatory, additional docstrings are forbidden. Added the R equivalent for roxygen #' blocks so the rule symmetric.

3. impl-review.yml — Python header rewrite needs a prepend fallback (#discussion_r3253434319)
The Python branch of the header-rewrite step ran re.sub on a triple-quoted docstring pattern and silently left the file unchanged if there was no header. Mirrors the R branch behaviour now: re.match first, prepend the canonical header if absent.

Deliberately not in this PR

• SHA-pinning r-lib/actions/setup-r and setup-renv (#discussion_r3253434287, #discussion_r3253434297). Pinning is correct policy, but pushing a SHA I haven't verified would re-introduce the bogus-SHA blocker that feat(ggplot2): add R/ggplot2 library + multi-language pipeline #6944 already had to fix. Dependabot will pin them to a verified SHA on its next run, the same way every other action ref in the repo got there.

Test plan

• python3 -c "import yaml; ..." on impl-review.yml — parses
• CI: ci-lint, ci-tests, frontend tsc + vitest
• One real impl-review run that exercises the Python prepend fallback (will happen organically the next time a Python impl is reviewed)

https://claude.ai/code/session_01Kb7b7QZi3ohtSTbd39poFV

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Generated by Claude Code

[Copilot]

Pull request overview

Small follow-up to PR #6944 (R/ggplot2 support) addressing three Copilot review comments: fix a hardcoded python label in the POTD terminal chip, clarify contradictory docstring guidance in the plot-generator prompt, and add a prepend fallback to the Python header-rewrite step in impl-review.

Changes:

• POTD terminal now derives runner (Rscript vs python) from potd.language, matching the existing .R/.py extension switch.
• Plot-generator prompt clarifies that the 4-line module header is mandatory while extra docstrings/roxygen blocks are forbidden (Python + R).
• impl-review.yml Python header rewrite uses re.match first and prepends the canonical header if absent, mirroring the R branch.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
app/src/components/PlotOfTheDayTerminal.tsx	Derive runner from language; replace hardcoded python chip text.
prompts/plot-generator.md	Resolve contradiction: mandatory header docstring, no extra docstrings/roxygen.
.github/workflows/impl-review.yml	Add prepend fallback when Python impl has no leading triple-quoted docstring.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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