feat(storage): Biz Connect folder in Files, manage storage, videos save once

Three connected pieces, so downloads stop being write-only.

1. A folder the user can actually find. ios-patch.sh now sets UIFileSharingEnabled
   and LSSupportsOpeningDocumentsInPlace, and downloads go to the app's Documents
   folder in typed subfolders. iOS shows it as:
       Files -> On My iPhone -> Biz Connect -> Images | Videos | Files
   Previously everything was written to CACHE (private, and iOS purges it whenever
   it likes) and pushed straight at the share sheet, so nothing was ever really
   "kept" by the app.

2. Manage storage (Settings -> Storage). Lists what this device has downloaded,
   grouped by type with per-group and total sizes; each row can be shared to the OS
   sheet (this is where "Save to Photos" now lives) or deleted. Plus Delete all.
   Deleting removes ONLY the local copy — the attachment stays on the server, so
   anything deleted can be downloaded again from the chat.

3. A downloaded video never downloads twice. Images and files have their own
   download link, but a video's tile IS the player, so it had no control at all and
   re-streamed on every play. It now carries a download button; once saved, the
   button becomes a tick and the tile plays from the local file — no network.

The index is treated as a cache of the filesystem, never as truth, because the user
can delete these from the Files app behind our back: every listing re-stats and
forgets what is gone, the library is reconciled at startup, and a local file that
has vanished by play time falls straight back to streaming instead of showing a
broken player.

Unit-checked the path allocator: collisions between different attachments with the
same filename resolve to "name (2)", re-downloading the SAME attachment reuses its
path, and path traversal / illegal characters are neutralised.

Note: the folder and the save location need a new iOS build to take effect. The web
side degrades cleanly — none of this UI appears outside the native app.

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

mobile/scripts/ios-patch.sh

@@ -30,6 +30,16 @@ BUILD_NO="${BUILD_NUMBER:-$(date +%s)}"
 echo "Setting CFBundleVersion = $BUILD_NO"
 set_str CFBundleVersion "$BUILD_NO"
 
+# ── Make the app's Documents folder visible in the Files app ───────────────────────────────────────
+# Downloads are saved to Documents/{Images,Videos,Files}. Without these two keys that folder is private
+# and the user has no way to reach what they saved. With them, Files shows
+#   Files → Browse → On My iPhone → Biz Connect → Images / Videos / Files
+# UIFileSharingEnabled exposes the folder; LSSupportsOpeningDocumentsInPlace lets other apps open those
+# files in place rather than silently working on a copy.
+set_bool() { "$PB" -c "Add :$1 bool $2" "$PLIST" 2>/dev/null || "$PB" -c "Set :$1 $2" "$PLIST"; }
+set_bool UIFileSharingEnabled            true
+set_bool LSSupportsOpeningDocumentsInPlace true
+
 # We use only standard encryption (HTTPS/TLS), which is exempt — declaring this up front stops App Store
 # Connect from asking the "export compliance" question on every single build/TestFlight upload.
 "$PB" -c "Add :ITSAppUsesNonExemptEncryption bool false" "$PLIST" 2>/dev/null \