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/build.gradle

@@ -0,0 +1,28 @@
+plugins { id 'fabric-loom' version '1.8.13' }
+def mc = providers.gradleProperty('mcVersion').getOrElse('1.21.1')
+if (!(mc in ['1.20.1', '1.21.1'])) throw new GradleException('Use the modern build for 26.x')
+def targetJava = mc == '1.20.1' ? 17 : 21
+loom { mixin { defaultRefmapName = 'scopenet.refmap.json' } }
+if (providers.gradleProperty('verifyMixins').isPresent()) {
+    loom { runs { server { vmArg '-Dscopenet.verifyMixins=true' } } }
+}
+java.sourceCompatibility = JavaVersion.toVersion(targetJava)
+java.targetCompatibility = JavaVersion.toVersion(targetJava)
+dependencies {
+    minecraft "com.mojang:minecraft:${mc}"
+    mappings loom.officialMojangMappings()
+    modImplementation 'net.fabricmc:fabric-loader:0.16.10'
+    implementation project(':common')
+}
+sourceSets.main.java.srcDirs += ['../minecraft/src/main/java', "../minecraft/src/${mc}/java"]
+sourceSets.main.resources.srcDirs += ['../minecraft/src/main/resources']
+apply from: '../minecraft/build-info.gradle'
+processResources {
+    inputs.properties(version: project.version, mc: mc, java: targetJava)
+    filesMatching('fabric.mod.json') { expand(version: project.version, mc: mc, java: targetJava) }
+}
+jar {
+    archiveBaseName = "scopenet-fabric-${mc}"
+    from project(':common').sourceSets.main.output
+}
+base.archivesName = "scopenet-fabric-${mc}"