Quick fixes from the first boot: recovery admin, upsell, warnings

- The recovery administrator (INBUXA_RECOVERY_ADMIN, or STALWART_RECOVERY_ADMIN)
  is honored only in bootstrap and recovery mode. On a configured server it's
  ignored with a startup warning. Before, it was a standing full-admin login
  for as long as the variable stayed set.
- The Enterprise upsell error is replaced by "This feature isn't available in
  INBUXA yet" for the features still to be rebuilt.
- Workspace warnings: 25 to 0. cargo fix removed the unused imports. The
  seven places where Enterprise code used to plug in keep their parameters,
  each with an inbuxa: comment naming the rebuild that uses it again. The
  antispam test's mock-server imports are back behind pending-rebuild.

crates/common/src/telemetry/mod.rs

@@ -96,7 +96,8 @@ impl Telemetry {
 }
 
 impl TelemetrySubscriberType {
-    pub fn spawn(self, builder: SubscriberBuilder, is_enterprise: bool) {
+    // inbuxa: `_is_enterprise` is unused until monitoring history is rebuilt, and goes when it is: there is one edition
+    pub fn spawn(self, builder: SubscriberBuilder, _is_enterprise: bool) {
         match self {
             TelemetrySubscriberType::ConsoleTracer(settings) => {
                 spawn_console_tracer(builder, settings)