docs: redesign README — centered hero, badges, feature grid, grouped features, collapsible config

- hero with app icon, CI/stack badges, deploy button, quick nav
- "why" grid, screenshots with captions, new year-insights card shot
- features grouped (live · analysis/forecast · resilience), dev/config details collapsed
- design/mockup.mjs: PIN from env (works against a deployed instance), snoozes the
  install nudge, and captures feature cards (battery health, forecast accuracy, year)
- .gitignore: local analysis reports and agent inbox (contain private data)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: THUNDER PHUM

.gitignore

@@ -20,3 +20,7 @@ design/shots/
 .mcp.json
 .summary/
 .uploads/
+
+# local analysis reports (contain device serials / private data) and agent inbox
+reports/
+.inbox/