chore(ui): retire the Building2 icon app-wide (#2235)

Founder request from the register walkthrough. Suppliers (nav, command
palette, empty state) use Truck; company and company-scoped surfaces
(active company badge, invite, home signpost, SIE preview, template
scopes, TIC workspace and its manifest) use Briefcase; the two bank
contexts use Landmark. The extension icon resolver no longer maps
Building2; the generated sector definitions follow the manifest.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

components/settings/ActiveCompanyBadge.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import { Building2 } from 'lucide-react'
+import { Briefcase } from 'lucide-react'
 import { useTranslations } from 'next-intl'
 import { cn } from '@/lib/utils'
 import { useCompany } from '@/contexts/CompanyContext'
@@ -33,7 +33,7 @@ export function ActiveCompanyBadge({ className }: { className?: string }) {
       )}
       title={`${t('active_company')}: ${company.name}`}
     >
-      <Building2 className="h-3 w-3 shrink-0" aria-hidden="true" />
+      <Briefcase className="h-3 w-3 shrink-0" aria-hidden="true" />
       <span className="sr-only">{t('active_company')}: </span>
       <span className="truncate">{company.name}</span>
     </Badge>