Fix Photos save for images + add native Quick Look file preview

Photos/Files bug: the lightbox download handed nativeSaveFile a bare
"/files/<id>" with no name, extension, or mime. Empty mime made
bzSaveToPhotos short-circuit as "notmedia" — so saveToAlbum (and its
permission prompt) never ran, and the image landed in the generic Files
folder as an extension-less blob. Now nativeSaveFile trusts the server's
Content-Type when the mime is unknown and appends a real extension
(bzExtForMime/bzEnsureExt), so images reach the Images folder AND Photos.

File preview: replace the @capacitor/share "share sheet" open with a new
native FileOpener plugin (QLPreviewController). bzOpenFile now prefers a
real Quick Look preview and only falls back to the share sheet if the
plugin isn't in the build. Wired file-opener into mobile/package.json and
the codemagic SPM diagnostics loop.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/public/home.html

@@ -2809,6 +2809,23 @@ function bzMimeFromName(n){
   if(/^(mp3|wav|m4a|aac|ogg|opus)$/.test(e)) return 'audio/'+e;
   return '';
 }
+// Map a MIME type to a file extension. Needed because some downloads arrive without one — the lightbox
+// hands us a bare "/files/<id>" (no name, no extension) — and a file saved with no extension is one that
+// neither the Photos app will accept nor the Files app / Quick Look can open.
+function bzExtForMime(mime){
+  const m=String(mime||'').toLowerCase().split(';')[0].trim();
+  const map={'image/jpeg':'jpg','image/jpg':'jpg','image/png':'png','image/gif':'gif','image/webp':'webp','image/heic':'heic','image/heif':'heif','image/bmp':'bmp','image/svg+xml':'svg',
+    'video/mp4':'mp4','video/quicktime':'mov','video/webm':'webm','video/3gpp':'3gp','video/x-matroska':'mkv','video/x-msvideo':'avi',
+    'audio/mpeg':'mp3','audio/mp4':'m4a','audio/aac':'aac','audio/wav':'wav','audio/x-wav':'wav','audio/ogg':'ogg','audio/opus':'opus',
+    'application/pdf':'pdf','application/zip':'zip','text/plain':'txt'};
+  if(map[m]) return map[m];
+  return (m.split('/')[1]||'').replace(/\+.*$/,'').replace(/[^a-z0-9]+/g,'').slice(0,5); // e.g. "svg+xml"→"svg"
+}
+function bzEnsureExt(name, mime){
+  const n=String(name||'file');
+  if(/\.[a-z0-9]{1,6}$/i.test(n)) return n;   // already carries an extension
+  const ext=bzExtForMime(mime); return ext ? n+'.'+ext : n;
+}
 function bzLibSrc(r){ try{ return r&&r.uri ? window.Capacitor.convertFileSrc(r.uri) : null; }catch(_){ return null; } }
 function bzPhotosOn(){ try{ return localStorage.getItem('bzc.photos')!=='off'; }catch(_){ return true; } }
 // Also put saved photos/videos in the Photos app, in a "Connect" album — the way WhatsApp does. The Files
@@ -2889,11 +2906,14 @@ function bzSyncFileTiles(only){
     el.title = saved ? 'Open' : 'Download to this device';
   });
 }
-// Open an already-downloaded file via the iOS share/preview sheet (Quick Look / open in another app). We have
-// no dedicated file-opener plugin, so @capacitor/share on the local file URI is the reliable "open".
+// Open an already-downloaded file. Prefer a native Quick Look PREVIEW (the FileOpener plugin) — that's the iOS
+// "look at this file" surface (swipe, pinch, print, its own share button), which is what people expect when
+// they tap a file. Only if the preview plugin isn't in this build do we fall back to the share sheet (which
+// offers "open in another app"), then to a new browser tab.
 async function bzOpenFile(rec, name){
   const uri=rec&&rec.uri; if(!uri) return;
   const P=window.Capacitor&&window.Capacitor.Plugins;
+  if(P&&P.FileOpener&&P.FileOpener.preview){ try{ await P.FileOpener.preview({ path:uri }); return; }catch(_){ /* fall through to the share sheet */ } }
   if(P&&P.Share){ try{ await P.Share.share({ title:name||'File', url:uri }); }catch(_){} return; } // catch = user cancelled
   try{ const src=bzLibSrc(rec); if(src) window.open(src, '_blank'); }catch(_){}
 }
@@ -2901,13 +2921,19 @@ async function nativeSaveFile(url, name, meta){
   const C=window.Capacitor, P=C&&C.Plugins; const Fs=P&&P.Filesystem;
   if(!Fs) return false;
   const id=(meta&&meta.id) || (String(url).split('?')[0].split('/').pop()||'');
-  const fname=(String(name||url.split('/').pop()||'file').replace(/[\/\\:*?"<>|\r\n]+/g,'_')).slice(0,120)||'file';
-  const mime=(meta&&meta.mime)||bzMimeFromName(fname);
+  let fname=(String(name||url.split('/').pop()||'file').replace(/[\/\\:*?"<>|\r\n]+/g,'_')).slice(0,120)||'file';
+  let mime=(meta&&meta.mime)||bzMimeFromName(fname);
   const onPct=(meta&&meta.onPct)||null;
   const box=onPct?null:bzDlShow(fname);   // a video reports % inside its own tile, so no floating chip
-  const lpath=bzLibPath(fname, mime, id);
   try{
     const res=await fetch(url, {credentials:'include'}); if(!res.ok) throw new Error('http '+res.status);
+    // The lightbox / avatar downloads hand us a bare "/files/<id>" — no name, no extension, no mime — so an
+    // image was landing in the generic "Files" folder as an extension-less blob and never reaching Photos.
+    // Trust the server's Content-Type here, then give the file a real extension, so it goes to the right
+    // folder, opens in Quick Look, AND qualifies for the Photos save below.
+    if(!mime){ mime=((res.headers.get('Content-Type')||'').split(';')[0]||'').trim().toLowerCase(); }
+    fname=bzEnsureExt(fname, mime);
+    const lpath=bzLibPath(fname, mime, id);
     const total=+(res.headers.get('Content-Length')||0);
     let uri=null, wrote=0;
     if(res.body && res.body.getReader){