pin filebrowser, couchdb, statping to explicit versions instead of floating beta/dev/untagged

Same category of risk as the gitea :nightly issue: floating dev/beta tags
let watchtower silently pull unvetted upstream builds. couchdb had no tag
at all (implicit :latest); filebrowser and statping only publish
beta/dev channels upstream so pinned to the exact version in use rather
than a moving target.

filebrowser-colleen-hd/docker-compose.yml

@@ -1,7 +1,10 @@
 services:
   filebrowser:
     container_name: filebrowser-colleen-hd
-    image: gtstef/filebrowser:beta
+    # No stable channel exists upstream for this project (only beta/preview
+    # tags are published) — pinned to the exact version in use instead of the
+    # floating :beta tag so watchtower can't silently jump versions.
+    image: gtstef/filebrowser:1.5.4-beta
     environment:
       FILEBROWSER_CONFIG: "data/config.yaml"
       TZ: "America/New_York"