feat(PROJ-12): E-Mail Export EML/PDF/ZIP

- GET /api/export/pdf/{id}: PDF-Generierung (stdlib, kein ext. Paket)
- POST /api/export/zip: Streaming-ZIP mit manifest.csv, Anhänge optional
- Max. 500 Mails pro Export, Zugriffscheck per Rolle
- Audit-Log für jeden Export
- Frontend: PDF-Button in Mail-Ansicht
- Frontend: Checkboxen + ZIP-Export-Dialog in Suchergebnissen

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/search/page.tsx

@@ -3,11 +3,20 @@
 import { useState, useCallback, useEffect } from "react";
 import { useRouter } from "next/navigation";
 import { useAuth } from "@/hooks/useAuth";
-import { searchEmails, type SearchHit } from "@/lib/api";
+import { searchEmails, exportMailsZIP, type SearchHit } from "@/lib/api";
 import { Navbar } from "@/components/navbar";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Card, CardContent } from "@/components/ui/card";
+import { Checkbox } from "@/components/ui/checkbox";
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from "@/components/ui/dialog";
 import {
   Table,
   TableBody,
@@ -18,6 +27,7 @@ import {
 } from "@/components/ui/table";
 import { Skeleton } from "@/components/ui/skeleton";
 import { Label } from "@/components/ui/label";
+import { Switch } from "@/components/ui/switch";
 
 const PAGE_SIZE = 25;
 
@@ -37,6 +47,17 @@ export default function SearchPage() {
   const [searching, setSearching] = useState(false);
   const [searched, setSearched] = useState(false);
 
+  // Selection state
+  const [selected, setSelected] = useState<Set<string>>(new Set());
+  const [exportOpen, setExportOpen] = useState(false);
+  const [exportAttachments, setExportAttachments] = useState(false);
+  const [exporting, setExporting] = useState(false);
+
+  // Clear selection when results change
+  useEffect(() => {
+    setSelected(new Set());
+  }, [results]);
+
   const doSearch = useCallback(
     async (p: number) => {
       setSearching(true);
@@ -87,7 +108,27 @@ export default function SearchPage() {
     doSearch(1);
   }
 
+  async function handleExportZIP() {
+    setExporting(true);
+    try {
+      const { blob } = await exportMailsZIP(Array.from(selected), exportAttachments);
+      const url = URL.createObjectURL(blob);
+      const a = document.createElement("a");
+      a.href = url;
+      a.download = "archivmail-export.zip";
+      a.click();
+      URL.revokeObjectURL(url);
+      setExportOpen(false);
+      setSelected(new Set());
+    } catch (e) {
+      alert(`Export fehlgeschlagen: ${e instanceof Error ? e.message : e}`);
+    } finally {
+      setExporting(false);
+    }
+  }
+
   const totalPages = Math.ceil(total / PAGE_SIZE);
+  const allSelected = results.length > 0 && results.every((h) => selected.has(h.id));
 
   if (authLoading || !user) {
     return (
@@ -189,10 +230,29 @@ export default function SearchPage() {
                   ? `${total} Ergebnis${total !== 1 ? "se" : ""} gefunden`
                   : `${total} E-Mail${total !== 1 ? "s" : ""} im Archiv`}
               </div>
+
+              {selected.size > 0 && (
+                <div className="mb-2 flex items-center gap-2">
+                  <span className="text-sm text-muted-foreground">{selected.size} ausgewählt</span>
+                  <Button size="sm" onClick={() => setExportOpen(true)}>Als ZIP exportieren</Button>
+                  <Button size="sm" variant="outline" onClick={() => setSelected(new Set())}>Auswahl aufheben</Button>
+                </div>
+              )}
+
               <Card>
                 <Table>
                   <TableHeader>
                     <TableRow>
+                      <TableHead className="w-10">
+                        <Checkbox
+                          checked={allSelected}
+                          onCheckedChange={(checked) => {
+                            if (checked) setSelected(new Set(results.map((h) => h.id)));
+                            else setSelected(new Set());
+                          }}
+                          aria-label="Alle auswählen"
+                        />
+                      </TableHead>
                       <TableHead className="w-32">Datum</TableHead>
                       <TableHead className="w-56">Von</TableHead>
                       <TableHead>Betreff</TableHead>
@@ -212,6 +272,20 @@ export default function SearchPage() {
                         }}
                         aria-label={`E-Mail von ${hit.from || "unbekannt"}: ${hit.subject || "Kein Betreff"}`}
                       >
+                        <TableCell onClick={(e) => e.stopPropagation()}>
+                          <Checkbox
+                            checked={selected.has(hit.id)}
+                            onCheckedChange={(checked) => {
+                              setSelected((prev) => {
+                                const next = new Set(prev);
+                                if (checked) next.add(hit.id);
+                                else next.delete(hit.id);
+                                return next;
+                              });
+                            }}
+                            aria-label="Mail auswählen"
+                          />
+                        </TableCell>
                         <TableCell className="whitespace-nowrap text-sm text-muted-foreground">
                           {hit.date
                             ? new Date(hit.date).toLocaleDateString("de-DE")
@@ -252,6 +326,33 @@ export default function SearchPage() {
             </>
           ) : null}
         </div>
+
+        <Dialog open={exportOpen} onOpenChange={setExportOpen}>
+          <DialogContent>
+            <DialogHeader>
+              <DialogTitle>E-Mails exportieren</DialogTitle>
+              <DialogDescription>
+                {selected.size} E-Mail{selected.size !== 1 ? "s" : ""} als ZIP herunterladen
+              </DialogDescription>
+            </DialogHeader>
+            <div className="flex items-center gap-3 py-2">
+              <Switch
+                id="attachments"
+                checked={exportAttachments}
+                onCheckedChange={setExportAttachments}
+              />
+              <Label htmlFor="attachments">Anhänge einschließen</Label>
+            </div>
+            <DialogFooter>
+              <Button variant="outline" onClick={() => setExportOpen(false)}>
+                Abbrechen
+              </Button>
+              <Button onClick={handleExportZIP} disabled={exporting}>
+                {exporting ? "Wird exportiert..." : "ZIP herunterladen"}
+              </Button>
+            </DialogFooter>
+          </DialogContent>
+        </Dialog>
       </main>
     </div>
   );