Message Logger: restore deep in long chats, media through the master, photo fixes

- Deleted messages within the loaded part of a long chat are placed by the
  app among the others (not only at the chat's end), without counting as
  unread; restores no longer repeat every second.
- Logger copies and their media are read through a member of the log group
  signed in here (this account, else the master); the shared file cache
  lets the current account show them.
- Logged chat photos: asked for once per 10 minutes, all sizes downloaded
  (no waits on inline thumbnails), added once the photo viewer closed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/api.py

@@ -99,6 +99,18 @@ class Api:
                 out.append((token[:10], exc))
         return out
 
+    def masters(self):
+        """Telegram ids of the tokens' masters (from /me), cached 10 minutes."""
+        cached = getattr(self, "_masters", None)
+        if cached is not None and time.monotonic() - cached[0] < 600:
+            return cached[1]
+        found = []
+        for _prefix, me in self.me():
+            if isinstance(me, dict) and me.get("master_tg_id"):
+                found.append(int(me["master_tg_id"]))
+        self._masters = (time.monotonic(), found)
+        return found
+
     def sync(self, account_id, chat_id, min_id, max_id, present_ids):
         body = {
             "account_id": account_id,