feat: model selection+visibility, better filenames, picdrop direct upload + configurable gallery

- studio: quality/model selector (friendly names from active models); library shows model used
- seed 2 models (Schnell/Beste Qualitaet); GET /api/models for studio+library
- filename: YYYY-MM-DD_motif_format.png (was redundant slug, no date)
- picdrop: direct upload to final name (fix .tmp- leftover from failed rename on picdrop); cleanupTmp helper
- configurable default gallery (migration 003, settings + admin field); base_path=SFTP root, gallery=subfolder

src/components/AdminApp.tsx

@@ -37,7 +37,7 @@ export default function AdminApp() {
   const saveSettings = async () => {
     const body: any = {
       picdrop_host: s.picdrop_host, picdrop_protocol: s.picdrop_protocol, picdrop_port: s.picdrop_port,
-      picdrop_user: s.picdrop_user, picdrop_base_path: s.picdrop_base_path,
+      picdrop_user: s.picdrop_user, picdrop_base_path: s.picdrop_base_path, picdrop_default_gallery: s.picdrop_default_gallery,
       default_dpi: s.default_dpi, default_crop_mode: s.default_crop_mode, concurrency: s.concurrency,
       cricut_sheet_cm: s.cricut_sheet_cm, monthly_budget: s.monthly_budget, n8n_webhook_url: s.n8n_webhook_url,
     };
@@ -126,7 +126,11 @@ export default function AdminApp() {
           </div>
           <div className="feld"><label>Passwort {s.picdrop_password_set && <em>(gesetzt)</em>}</label>
             <input className="input" type="password" placeholder={s.picdrop_password_set ? '••••••' : ''} value={pdPw} onChange={(e) => setPdPw(e.target.value)} /></div>
-          <div className="feld"><label>Basisordner</label><input className="input" value={s.picdrop_base_path ?? '/'} onChange={(e) => field('picdrop_base_path', e.target.value)} /></div>
+          <div className="zwei">
+            <div className="feld"><label>Basisordner (SFTP-Wurzel)</label><input className="input" value={s.picdrop_base_path ?? '/'} onChange={(e) => field('picdrop_base_path', e.target.value)} /></div>
+            <div className="feld"><label>Standard-Galerie</label><input className="input" placeholder="POSTER LEA" value={s.picdrop_default_gallery ?? ''} onChange={(e) => field('picdrop_default_gallery', e.target.value)} /></div>
+          </div>
+          <div className="fein">Bilder landen in <b>Basisordner / Galerie</b> — z. B. <code>/ + POSTER LEA</code>. Pro Ordner lässt sich später eine eigene Galerie mappen.</div>
         </div>
       </section>