fix(debug): sweep expired paste.rs uploads on a real timer (#16431)

Previously 'hermes debug share' uploads only got DELETEd when the user
ran 'hermes debug share' again — opportunistic-sweep-on-invoke was the
only cleanup path. A user who uploaded once and never ran debug again
left pastes up until paste.rs's retention kicked in (which, empirically,
never actually expires them).

Hook _sweep_expired_pastes into the gateway cron ticker at the same
hourly cadence as the image/document cache cleanups. The opportunistic
sweep in 'hermes debug share' stays as a fallback for CLI-only users
who never start the gateway.

gateway/run.py

@@ -11153,13 +11153,16 @@ def _start_cron_ticker(stop_event: threading.Event, adapters=None, loop=None, in
     cron delivery path so live adapters can be used for E2EE rooms.
 
     Also refreshes the channel directory every 5 minutes and prunes the
-    image/audio/document cache once per hour.
+    image/audio/document cache + expired ``hermes debug share`` pastes
+    once per hour.
     """
     from cron.scheduler import tick as cron_tick
     from gateway.platforms.base import cleanup_image_cache, cleanup_document_cache
+    from hermes_cli.debug import _sweep_expired_pastes
 
     IMAGE_CACHE_EVERY = 60   # ticks — once per hour at default 60s interval
     CHANNEL_DIR_EVERY = 5    # ticks — every 5 minutes
+    PASTE_SWEEP_EVERY = 60   # ticks — once per hour
 
     logger.info("Cron ticker started (interval=%ds)", interval)
     tick_count = 0
@@ -11200,6 +11203,17 @@ def _start_cron_ticker(stop_event: threading.Event, adapters=None, loop=None, in
             except Exception as e:
                 logger.debug("Document cache cleanup error: %s", e)
 
+        if tick_count % PASTE_SWEEP_EVERY == 0:
+            try:
+                deleted, remaining = _sweep_expired_pastes()
+                if deleted:
+                    logger.info(
+                        "Paste sweep: deleted %d expired paste(s), %d pending",
+                        deleted, remaining,
+                    )
+            except Exception as e:
+                logger.debug("Paste sweep error: %s", e)
+
         stop_event.wait(timeout=interval)
     logger.info("Cron ticker stopped")