Bash common.sh: consolidate docker_cmd/retry_docker/verify_running/emby_api, fix tailscale dups

common.sh gains:
- docker_cmd() + verify_running() + retry_docker() — removed from all 3 Docker_Essentials
  scripts where they were byte-for-byte duplicates
- emby_api(endpoint, [timeout=30]) — removed from 6 Media/Tools scripts that each defined
  their own _emby_api() with the same curl/parse/error pattern; call sites renamed emby_api
- format_duration() extended with days/hours branch (was capped at minutes+seconds)
- notify() comment: scripts do not need to preflight the notify script via validate_unraid_cmd

Tailscale deduplication:
- arr_sync.sh: _resolve_node_ip() and inline block in _delete_remote_item() both replaced
  with resolve_tailscale_ip() from common.sh
- git_pull_execute.sh: inline tailscale ip -4 replaced with resolve_tailscale_ip() (adds
  the tailscale status fallback that was missing)

git_pull_execute.sh

@@ -82,7 +82,7 @@ if docker ps --format "{{.Names}}" 2>/dev/null | grep -q "^${GITEA_CONTAINER}$";
 else
     # Gitea not running locally — find it on the remote server via Tailscale
     log "Gitea not running locally — checking remote server"
-    GITEA_IP=$(tailscale ip -4 "${REMOTE_SERVER_NAME,,}" 2>/dev/null)
+    GITEA_IP=$(resolve_tailscale_ip "${REMOTE_SERVER_NAME}")
     if [[ -n "$GITEA_IP" ]]; then
         echo "  Gitea on $REMOTE_SERVER_NAME — connecting via Tailscale $GITEA_IP"
     elif [[ -n "${GITEA_DOMAIN:-}" ]]; then