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.

integrations/fabric/src/main/java/net/scopenet/fabric/ScopenetFabric.java

@@ -0,0 +1,11 @@
+package net.scopenet.fabric;
+
+import net.fabricmc.api.DedicatedServerModInitializer;
+
+/** Server-only; lifecycle and admission hooks are shared mixins. */
+public final class ScopenetFabric implements DedicatedServerModInitializer {
+    @Override public void onInitializeServer() {
+        if (Boolean.getBoolean("scopenet.verifyMixins"))
+            org.spongepowered.asm.mixin.MixinEnvironment.getCurrentEnvironment().audit();
+    }
+}

integrations/fabric/src/main/resources/fabric.mod.json

@@ -0,0 +1,10 @@
+{
+  "schemaVersion": 1,
+  "id": "scopenet",
+  "version": "${version}",
+  "name": "SCOPENET",
+  "environment": "server",
+  "entrypoints": { "server": ["net.scopenet.fabric.ScopenetFabric"] },
+  "mixins": ["scopenet.mixins.json"],
+  "depends": { "fabricloader": ">=0.16.10", "minecraft": "${mc}", "java": ">=${java}" }
+}