feat: improve invoice view responsiveness and settings UX

- Replace custom invoice items table with responsive DataTable component
- Fix server/client component error by creating InvoiceItemsTable client
  component
- Merge danger zone with actions sidebar and use destructive button
  variant
- Standardize button text sizing across all action buttons
- Remove false claims from homepage (testimonials, ratings, fake user
  counts)
- Focus homepage messaging on freelancers with honest feature
  descriptions
- Fix dark mode support throughout app by replacing hard-coded colors
  with semantic classes
- Remove aggressive red styling from settings, add subtle red accents
  only
- Align import/export buttons and improve delete confirmation UX
- Update dark mode background to have subtle green tint instead of pure
  black
- Fix HTML nesting error in AlertDialog by using div instead of nested p
  tags

This update makes the invoice view properly responsive, removes
misleading marketing claims, and ensures consistent dark mode support
across the entire application.

src/app/dashboard/invoices/import/page.tsx

@@ -5,7 +5,7 @@ import { Card, CardContent, CardHeader, CardTitle } from "~/components/ui/card";
 import { Button } from "~/components/ui/button";
 import { Badge } from "~/components/ui/badge";
 import { Separator } from "~/components/ui/separator";
-import { PageHeader } from "~/components/page-header";
+import { PageHeader } from "~/components/layout/page-header";
 import {
   ArrowLeft,
   Upload,