feat: Add SVG and PDF vector export for statistical plots

[dataCenter430]

PR Description

This pull request adds vector format export (SVG and PDF) for statistical plots, enabling publication-ready figures for academic venues such as NeurIPS, ICML, and ICLR with no new dependencies.

Related Issue: Closes #97

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Key Changes

New CLI Flag (paperbanana generate):

• --vector / --no-vector — exports SVG and PDF alongside the raster output for statistical plots
• Non-breaking; defaults to False, leaving MCP server and batch runner unaffected

VisualizerAgent (paperbanana/agents/visualizer.py):

• _execute_plot_code() — strips any VLM-injected VECTOR_PATH_* assignments, injects authoritative VECTOR_PATH_SVG / VECTOR_PATH_PDF variables into the script header, and appends plt.savefig() calls for each requested format after user code
• run() / _generate_plot() — accept vector_formats parameter; results stored in self._last_vector_paths after each execution
• State is reset to {} at the start of every run() call to prevent bleed between iterations

Settings (paperbanana/core/config.py):

• vector_export: bool = False — new field on Settings
• VectorFormat = Literal["svg", "pdf"] — type alias for valid vector formats
• YAML key output.vector_export supported via _flatten_yaml

Pipeline (paperbanana/core/pipeline.py):

• Derives vector_formats from settings.vector_export in both generate() and continue_run()
• Writes vector_output_paths dict to metadata.json when vector files are produced
• Vector export is silently skipped for methodology diagrams (image-gen path, not matplotlib)

Usage

# JSON
paperbanana plot --data results.json --intent "..." --vector

# CSV
paperbanana plot --data results.csv --intent "..." --vector



Output when --vector is used:

Done! Plot saved to: outputs/run_.../final_output.png
Vector (SVG): outputs/run_.../plot_iter_1.svg
Vector (PDF): outputs/run_.../plot_iter_1.pdf

[dataCenter430]

Hi, @dippatel1994 I hope you're doing well.
This is my first PR, would you plesae review the PR?
Please share me your feedback fully.
Thank you.

[dippatel1994]

Good feature design. Three things to fix:

1. Windows tests fail — path injection bug — VECTOR_PATH_{fmt} = "{vec_path}" uses f-string with unescaped backslashes. On Windows, C:\Users\... has \U which is an invalid unicode escape → SyntaxError. Fix with repr(path) or path.replace('\\', '/'). Same pre-existing bug on OUTPUT_PATH — fix both while you're here.

2. Lint fails — 3 ruff errors: two E501 (line too long) in visualizer.py and cli.py, one F401 (unused import pytest) in test file.

3. VectorFormat type alias defined but never used — paperbanana/core/config.py adds VectorFormat = Literal["svg", "pdf"] but it's never imported or referenced. Either use it to type-annotate vector_formats or remove it.

[dataCenter430]

Thanks for your response, @dippatel1994
I understood the CI failure cause fully.
I will them you mentioned soon.
Thank you.

[dippatel1994]

Windows path bug and VectorFormat removal are fixed, nice work. Tests all pass now including Windows.

Lint still fails though. It's a formatting issue, not a code error. Run ruff format paperbanana/agents/visualizer.py tests/test_agents/test_visualizer.py and push.

[dataCenter430]

Windows path bug and VectorFormat removal are fixed, nice work. Tests all pass now including Windows.

Lint still fails though. It's a formatting issue, not a code error. Run ruff format paperbanana/agents/visualizer.py tests/test_agents/test_visualizer.py and push.

Okay, thanks for your active response.
I will do it right now.

[dataCenter430]

Just done!
now it should work successfully.
Really hope your review again.
Thanks

[dippatel1994]

All issues fixed. Windows path bug resolved, lint clean, VectorFormat removed. CI fully green. LGTM.