fix(monitoring): hostname, tooltip timestamps, default range (v0.5.1)

- Bug 1: Read hostname from /host/etc/hostname instead of os.Hostname()
  which returns the container ID inside Docker. Added volume mount.
- Bug 2: Tooltip callback used parsed.x (category index) instead of
  label (actual timestamp), showing 1970 dates.
- Bug 3+4: Default range changed from 24h to 1h so charts show data
  immediately on new deployments with limited history.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/docker-compose.yml

@@ -27,6 +27,8 @@ services:
       - /sys:/host/sys:ro
       # Host OS info — for monitoring page system info
       - /etc/os-release:/host/etc/os-release:ro
+      # Host hostname — for monitoring page (os.Hostname() returns container ID)
+      - /etc/hostname:/host/etc/hostname:ro
     environment:
       - TZ=Europe/Budapest
     labels: