feat: polish landing page first-contact flow

[volcano303]

Summary

Polishes the landing page first-contact flow for new visitors while preserving the PR #950 visual direction and keeping the change focused on the landing experience.

• Clarifies the Gittensor loop: miners contribute to tracked repositories, validators review useful merged work, and reward estimates update from live GitHub activity.
• Strengthens the first-contact proof sections with live work/top miner panels, clearer "How Gittensor works" copy, KPI treatment, maintainer/miner CTAs, and responsive layout polish.
• Hardens dashboard/landing data composition so non-array or unavailable API responses render empty states instead of crashing the page.
• Keeps PR feat: polish landing page first-contact flow and proof sections #1089's useful landing-page direction, but avoids the extra Vite proxy configuration scope for a cleaner merge-ready patch.

Related Issues

Fixes #970

Related to #877, #950, #971, #994, and #1089.

Type of Change

• Bug fix
• New feature
• Refactor
• Documentation
• Other (describe below)

Screenshots

Captured locally during validation:

• Desktop: /tmp/gittensor-home-test-api-desktop.png
• Mobile: /tmp/gittensor-home-test-api-mobile.png

Checklist

• New components are modularized/separated where sensible
• Uses predefined theme (e.g. no hardcoded colors)
• Responsive/mobile checked
• Tested against the test API
• npm run format and npm run lint:fix have been run
• npm run build passes
• Screenshots included for any UI/visual changes

[anderdc]

Duplicate of #1089 which is better scoped/implemented. Closing.