feat(mobile): touch up new-invoice + scan-receipt forms

- new invoice: push "New Invoice" to mobile topbar, hide the
    redundant inline back+title row on mobile.
  - scan receipt: dedicated "Take photo" primary button on mobile
    (uses input capture="environment" to open the camera directly)
    plus "Choose from library" secondary. Drop-zone framing kept on
    desktop. Push "Scan Receipt" title to mobile topbar.

Both forms now take their entity title from the topbar and free up
real-estate at the top for actual content.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/(dashboard)/[portSlug]/invoices/new/page.tsx

@@ -1,12 +1,14 @@
 'use client';
 
-import { useState } from 'react';
+import { useEffect, useState } from 'react';
 import { useParams, useRouter } from 'next/navigation';
 import { useForm, FormProvider } from 'react-hook-form';
 import { zodResolver } from '@hookform/resolvers/zod';
 import { useMutation } from '@tanstack/react-query';
 import { ChevronLeft, ChevronRight, Check, Loader2 } from 'lucide-react';
 
+import { useMobileChrome } from '@/components/layout/mobile/mobile-layout-provider';
+
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Label } from '@/components/ui/label';
@@ -46,6 +48,12 @@ export default function NewInvoicePage() {
 
   const [step, setStep] = useState(1);
 
+  const { setChrome } = useMobileChrome();
+  useEffect(() => {
+    setChrome({ title: 'New Invoice', showBackButton: true });
+    return () => setChrome({ title: null, showBackButton: false });
+  }, [setChrome]);
+
   const methods = useForm<CreateInvoiceInput>({
     resolver: zodResolver(createInvoiceSchema),
     defaultValues: {
@@ -117,8 +125,8 @@ export default function NewInvoicePage() {
 
   return (
     <div className="max-w-2xl mx-auto space-y-6">
-      {/* Header */}
-      <div className="flex items-center gap-3">
+      {/* Header — desktop only; mobile gets the title from the topbar */}
+      <div className="hidden sm:flex items-center gap-3">
         <Button variant="ghost" size="sm" onClick={() => router.push(`/${portSlug}/invoices`)}>
           <ChevronLeft className="h-4 w-4" />
         </Button>