fix: add colored contours visual outputs for GitHub Pages showcase

[krystophny]

Summary

• Fixed colored contours output visibility issue on GitHub Pages (No output visible on https://lazy-fortran.github.io/fortplot/page/examples/colored_contours.html #329)
• Added all PNG and PDF output files to doc/media/examples/colored_contours/
• Updated colored_contours.md with proper image references and ASCII output sections
• Followed established documentation pattern from working examples (pcolormesh_demo)

Root Cause Analysis

The colored_contours example was not displaying visual output on GitHub Pages because:

1. Missing media files: No PNG/PDF files were present in doc/media/examples/colored_contours/
2. Incomplete documentation: colored_contours.md lacked image references and ASCII output sections
3. Documentation inconsistency: Did not follow the established pattern used by working examples

Implementation

Files Added

• doc/media/examples/colored_contours/gaussian_default.png/pdf - 2D Gaussian with colorblind-safe default colormap
• doc/media/examples/colored_contours/saddle_plasma.png/pdf - Saddle function with plasma colormap
• doc/media/examples/colored_contours/ripple_jet.png/pdf - Ripple pattern with jet colormap
• doc/media/examples/colored_contours/ripple_coolwarm.png/pdf - Ripple pattern with coolwarm colormap
• doc/media/examples/colored_contours/ripple_inferno.png/pdf - Ripple pattern with inferno colormap

Documentation Updated

• Added proper image references: ![filename.png](../../media/examples/colored_contours/filename.png)
• Included complete ASCII output sections for each colormap variant
• Added PDF download links for each example
• Followed exact format pattern from pcolormesh_demo.md

Test Plan

• Run colored_contours example successfully
• Verify all output files generated in output/example/fortran/colored_contours/
• Copy PNG and PDF files to doc/media/examples/colored_contours/
• Update documentation with image references and ASCII output
• Verify documentation follows established pattern
• Commit and push changes

Results

The colored_contours example now provides a complete visual showcase on GitHub Pages with:

• 5 different colormap demonstrations (crest, plasma, jet, coolwarm, inferno)
• Proper PNG image display
• Complete ASCII art output for terminal viewing
• PDF download links for high-quality versions
• Consistent documentation format across all examples

Fixes #329

🤖 Generated with Claude Code

Co-Authored-By: Claude noreply@anthropic.com

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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