feat: add supporting data capture, PDF export, and branding settings UI

- API clients for supporting data CRUD and team branding
- AddSupportingDataModal with text snippet and screenshot tabs (paste + upload)
- SupportingDataPanel collapsible section integrated into both session runners
- ExportPreviewModal updated with PDF format and server-side download flow
- BrandingSettings component for company name and logo management
- Expose team_id in UserResponse schema for branding endpoint access

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/pages/SessionDetailPage.tsx

@@ -32,7 +32,7 @@ export function SessionDetailPage() {
   const [isLoading, setIsLoading] = useState(true)
   const [error, setError] = useState<string | null>(null)
   const [isExporting, setIsExporting] = useState(false)
-  const [exportFormat, setExportFormat] = useState<'markdown' | 'text' | 'html' | 'psa'>(defaultExportFormat)
+  const [exportFormat, setExportFormat] = useState<'markdown' | 'text' | 'html' | 'psa' | 'pdf'>(defaultExportFormat)
   const [exportContent, setExportContent] = useState<string | null>(null)
   const [showPreview, setShowPreview] = useState(false)
   const [copied, setCopied] = useState(false)
@@ -51,6 +51,7 @@ export function SessionDetailPage() {
   const [redactionMode, setRedactionMode] = useState<'none' | 'mask'>('none')
   const [redactionSummary, setRedactionSummary] = useState<RedactionSummary | null>(null)
   const [isGeneratingFlow, setIsGeneratingFlow] = useState(false)
+  const [pdfLoading, setPdfLoading] = useState(false)
 
   useEffect(() => {
     if (id) {
@@ -223,6 +224,31 @@ export function SessionDetailPage() {
     }
   }
 
+  const handleDownloadPdf = async () => {
+    if (!session) return
+    setPdfLoading(true)
+    try {
+      const { apiClient } = await import('@/api/client')
+      const response = await apiClient.post(
+        `/sessions/${session.id}/export`,
+        { format: 'pdf' },
+        { responseType: 'blob' }
+      )
+      const url = URL.createObjectURL(response.data)
+      const a = document.createElement('a')
+      a.href = url
+      a.download = `session-export-${session.id}.pdf`
+      a.click()
+      URL.revokeObjectURL(url)
+      analytics.exportGenerated({ session_id: session.id, format: 'pdf' })
+    } catch (error) {
+      console.error('PDF export failed:', error)
+      toast.error('Failed to generate PDF export')
+    } finally {
+      setPdfLoading(false)
+    }
+  }
+
   const handleSaveAsTree = async (data: SaveAsTreeRequest) => {
     if (!session) return
     setIsSavingTree(true)
@@ -478,6 +504,7 @@ export function SessionDetailPage() {
           <option value="text">Plain Text</option>
           <option value="html">HTML</option>
           <option value="psa">PSA / Ticket Note</option>
+          <option value="pdf">PDF</option>
         </select>
         {session.decisions.length > 1 && (
           <select
@@ -546,6 +573,8 @@ export function SessionDetailPage() {
         filename={getFilename()}
         format={exportFormat}
         onDownload={handleDownload}
+        onDownloadPdf={handleDownloadPdf}
+        pdfLoading={pdfLoading}
         includeSummary={includeSummary}
         onToggleSummary={handleToggleSummary}
         redactionEnabled={redactionMode === 'mask'}