Recreate Next.js source — shadcn components, chart, types, hooks

Source files were untracked and lost during reset. Recreated:
- page.tsx (full 3-tab dashboard), layout.tsx, globals.css (shadcn theme)
- types.ts, api.ts, utils.ts
- strategy-card.tsx, equity-chart.tsx, positions-panel.tsx
- ui/ (7 shadcn wrappers: card, badge, button, table, tabs, sheet, collapsible, select)
- Config files: next.config.ts, tsconfig.json, postcss.config.mjs, components.json

dashboard-next/.gitignore

@@ -0,0 +1,5 @@
+node_modules/
+.next/
+out/
+out-www/
+_next-app-backup/