Refactor/core qol adoption (#17655)

* Scripts: close every msg_info block with msg_ok

Past-tense msg_info calls that should have been msg_ok, notices that opened a block before a prompt, and blocks without a closing msg_ok. These already left a stale spinner; with core's block stack they would resume it after every later msg_ok.

* Generate passwords with random_password

openssl rand -base64 | tr -dc | head -c returned fewer characters than asked for, and the unfiltered | cut variants put / and + into passwords that end up in DSNs and sed expressions. Secrets an app decodes as base64 are unchanged. Requires community-scripts/core#61.

* Keep data directories through CLEAN_INSTALL instead of copying them

create_backup copied uploads, storage and similar directories twice per update and needed their size again in free space. CLEAN_INSTALL_KEEP moves them aside instead. Only directories the upstream release does not ship, in scripts that restored right after the fetch. Requires community-scripts/core#61.

* Drop the 300s uv timeout overrides

setup_uv exports UV_HTTP_TIMEOUT=600 now; the scripts' 300 only lowered it. Requires community-scripts/core#61.

install/fileflows-install.sh

@@ -54,12 +54,11 @@ if [[ "$install_server" =~ ^[Ss]$ ]]; then
   systemctl enable -q --now fileflows
   msg_ok "Installed FileFlows Server"
 else
-  msg_info "Installing FileFlows Agent"
-  stop_spinner
   read -r -p "${TAB3}Enter FileFlows Server URL (e.g. http://192.168.1.10:19200): " server_url
   while [[ -z "${server_url// /}" ]]; do
     read -r -p "${TAB3}Enter FileFlows Server URL (e.g. http://192.168.1.10:19200): " server_url
   done
+  msg_info "Installing FileFlows Agent"
   cd /opt/fileflows/Agent
   before_units="$(systemctl list-unit-files 'fileflows*' --no-legend 2>/dev/null | awk '{print $1}' | sort || true)"
   $STD dotnet FileFlows.Agent.dll --server "$server_url" --systemd install --root true