fix: persist diagnostics opt-in inside containers for addon telemetry

- install.func + alpine-install.func: create /usr/local/community-scripts/diagnostics
  inside the container when DIAGNOSTICS=yes (from build.func export)
- Enables addon scripts running later inside containers to find the opt-in
- Update init_tool_telemetry default type from 'tool' to 'pve'

misc/install.func

@@ -37,6 +37,13 @@ source <(curl -fsSL https://raw.githubusercontent.com/community-scripts/ProxmoxV
 load_functions
 catch_errors
 
+# Persist diagnostics opt-in inside container (exported from build.func)
+# so addon scripts running later can find it
+if [[ "${DIAGNOSTICS:-no}" == "yes" ]] && [[ ! -f /usr/local/community-scripts/diagnostics ]]; then
+  mkdir -p /usr/local/community-scripts
+  echo "DIAGNOSTICS=yes" >/usr/local/community-scripts/diagnostics
+fi
+
 # Get LXC IP address (must be called INSIDE container, after network is up)
 get_lxc_ip