rename appdata-Failover→appdata-Fallback in docs; critical sync 15→30min; transcode 3→7min

appdata-Failover → appdata-Fallback:
  All .md files updated — scripts and confs already used appdata-Fallback.
  Share was renamed; docs were the only stale references.

critical_sync_maintenance.sh: */15 → */30, 96/day → 48/day:
  critical_sync_maintenance.sh header, master.conf, host1/2.conf comments,
  Orchestrators README, User Script Plug-in README, Partnership README/manual/script,
  Docker_Essentials README/downloaders_reset.sh, Fallback README,
  weekly_sync_maintenance.sh, user_script_plug-in.sh all updated.

rsync_emby_failover User Script superseded:
  Emby dirty sync was already in HOST1_CRITICAL_SYNC_SHARES — it now runs inside
  critical_sync_maintenance.sh every 30min alongside auth sync and partnership check.
  Section in User Script Plug-in README marked for deletion from plugin.

transcode_management.sh: */3 → */7:
  transcode_management.sh, transcode_manager.sh, transcode_cleanup.sh headers,
  Transcodes README/manual, Orchestrators README, User Script Plug-in README,
  user_script_plug-in.sh all updated.

Transcodes/transcode_cleanup.sh

@@ -20,7 +20,7 @@
 #
 # lsof Called Once, Not Per File
 #   On a busy Live TV system the ramdisk contains thousands of HLS segment files.
-#   Calling lsof once per file creates thousands of subprocess calls every 3 minutes.
+#   Calling lsof once per file creates thousands of subprocess calls every 7 minutes.
 #   lsof is called once per location to build a complete open-file map. All subsequent
 #   checks are O(1) lookups against that map — thousands of files, one lsof call.
 #
@@ -59,7 +59,7 @@
 #   `! -name "transcoding-temp"` in the find command — protected unconditionally.
 #
 # Silent by Default
-#   Runs every 3 minutes — must not produce noise when healthy.
+#   Runs every 7 minutes — must not produce noise when healthy.
 #
 # ==============================================================================================
 # CONFIGURATION