feat: add comprehensive E2E tests with Docker workflow

- Add comprehensive.e2e.test.ts: Full E2E tests covering 25+ converters
- Add format-matrix.e2e.test.ts: Format conversion matrix (70,000+ combinations)
- Add translation.e2e.test.ts: Multi-language translation tests (14 languages)
- Add docker-e2e-tests.yml: GitHub Actions workflow for Docker E2E tests
- Update run-bun-test.yml: Improved basic test workflow
- Add run-e2e-tests.sh: Local test runner script
- Add test scripts to package.json

Tests cover:
- Image formats (Inkscape, ImageMagick, Potrace, etc.)
- Document formats (Pandoc, LibreOffice, Calibre)
- Data formats (Dasel: JSON/YAML/TOML/XML/CSV)
- Translation (PDFMathTranslate, BabelDOC)
- Edge cases (Unicode, long content, special characters)

tests/e2e/fixtures/sample.tex

@@ -0,0 +1,28 @@
+\documentclass{article}
+\usepackage{fontspec}
+\usepackage{xeCJK}
+\setCJKmainfont{Noto Sans CJK SC}
+
+\begin{document}
+
+\section{Introduction}
+
+This is a test document for translation testing.
+The quick brown fox jumps over the lazy dog.
+
+\section{Technical Content}
+
+Machine learning is a subset of artificial intelligence.
+Neural networks are inspired by the human brain.
+
+\subsection{Mathematical Formulas}
+
+$E = mc^2$
+
+$\int_0^\infty e^{-x^2} dx = \frac{\sqrt{\pi}}{2}$
+
+\section{Conclusion}
+
+This document is used for testing multilingual translation capabilities.
+
+\end{document}