Complete private authentication, server integrations and activity reporting

Add Fabric/Forge version builds and Paper integration, preserve permanent player identities across renames, harden session authorization, and surface privacy-conscious launcher/server activity in the panel.

panel/server/src/yggdrasil/mod.rs

@@ -424,8 +424,8 @@ async fn has_joined(State(state): State<AppState>, headers: HeaderMap, Query(q):
     if !user.username.eq_ignore_ascii_case(&q.username) {
         return Ok(no_content());
     }
-    if let (Some(expected), Some(actual)) = (q.ip.as_deref().filter(|i| !i.is_empty()), joined_ip.as_deref()) {
-        if expected != actual {
+    if let Some(expected) = q.ip.as_deref().filter(|i| !i.is_empty()) {
+        if joined_ip.as_deref() != Some(expected) {
             return Ok(no_content());
         }
     }