Add GitHub repo and homepage links to project cards (fixes #37)

[Copilot]

• [x] Add GitHub repo and homepage links to project cards (fixes #37)
• [x] Convert template blocks to use ES template literals
• [x] Convert all variables to use const and let instead of var
• [x] Convert remaining function expressions to arrow functions
• [x] Replace string concatenation with template literals in html5prettyDate
• [x] Update external script loader to use arrow functions

All code now uses modern ES6+ syntax throughout:

• ✅ Template literals with backticks for all string templates
• ✅ const and let declarations instead of var
• ✅ Arrow functions for callbacks and anonymous functions
• ✅ Consistent modern JavaScript patterns

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