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/new/page.tsx

@@ -10,7 +10,7 @@ import { Input } from "~/components/ui/input";
 import { NumberInput } from "~/components/ui/number-input";
 import { Label } from "~/components/ui/label";
 import { Textarea } from "~/components/ui/textarea";
-import { PageHeader } from "~/components/page-header";
+import { PageHeader } from "~/components/layout/page-header";
 import {
   Select,
   SelectContent,
@@ -32,7 +32,7 @@ import {
 import { Badge } from "~/components/ui/badge";
 import { Separator } from "~/components/ui/separator";
 import { DatePicker } from "~/components/ui/date-picker";
-import { FloatingActionBar } from "~/components/ui/floating-action-bar";
+import { FloatingActionBar } from "~/components/layout/floating-action-bar";
 import { toast } from "sonner";
 import {
   ArrowLeft,