docs: revamp README for public audience

[google-labs-jules]

Revamped the README.md to be more compelling for a public audience by:

• Adding a "Why Kindred?" section
• Adding a Features Showcase table
• Highlighting a quick 30-second Docker setup
• Adding a placeholder for a Demo GIF
• Adding a "Tech Stack" and a "Comparison to other tools" section
• Reordering and preserving all existing technical documentation securely under a new "Technical Documentation" banner.

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PR created automatically by Jules for task 18303792697183642768 started by @pike00

[google-labs-jules]

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