Add documentation dark mode and navigation tracking

[google-labs-jules]

This PR introduces a micro-UX improvement to the project's documentation and a developer experience (DX) polish to the project initialization script.

💡 What: The UX enhancement added

• Documentation Polish: Added a dark mode toggle and navigation tracking to the MkDocs configuration (mkdocs.yml).
• Initialization Fix: Replaced non-portable sed -i commands in the Makefile with perl -i -pe to ensure the make project command works correctly on both macOS and Linux.
• Journaling: Created .Jules/palette.md to track UX and accessibility learnings.

🎯 Why: The user problem it solves

• Accessibility & UX: Dark mode reduces eye strain and improves readability in low-light environments. Navigation tracking helps users keep track of their position on long documentation pages.
• Developer Experience: The previous sed usage was breaking on Linux environments, hindering the "out of the box" experience for new developers.

♿ Accessibility: Any a11y improvements made

• Added a dark mode toggle using standard MkDocs Material palette settings, allowing users to choose the theme that best suits their visual needs.

📸 Before/After

• Before: Static light theme documentation; broken make project command on Linux.
• After: Documentation with theme toggle and smooth navigation; portable project initialization.

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PR created automatically by Jules for task 6707510982421446355 started by @amrabed

[google-labs-jules]

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