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.

.github/workflows/integrations.yml

@@ -0,0 +1,74 @@
+name: Server integrations
+
+on:
+  push:
+    branches: ['**']
+    paths: ['integrations/**', '.github/workflows/integrations.yml']
+  pull_request:
+    paths: ['integrations/**', '.github/workflows/integrations.yml']
+  workflow_dispatch:
+  workflow_call:
+    inputs:
+      version:
+        type: string
+        default: '0.1.0'
+
+permissions:
+  contents: read
+
+jobs:
+  paper:
+    name: Paper and protocol tests
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-java@v5
+        with:
+          distribution: temurin
+          java-version: '21'
+      - uses: gradle/actions/setup-gradle@v4
+        with:
+          gradle-version: '8.10.2'
+      - run: gradle -p integrations :common:test :paper:build -PreleaseVersion="${{ inputs.version || '0.1.0' }}"
+      - uses: actions/upload-artifact@v4
+        with:
+          name: server-paper
+          path: integrations/paper/build/libs/scopenet-paper-*.jar
+          if-no-files-found: error
+      - uses: actions/upload-artifact@v4
+        if: failure()
+        with:
+          name: integration-test-reports
+          path: integrations/common/build/reports/tests/
+
+  mods:
+    name: ${{ matrix.loader }} / ${{ matrix.mc.version }}
+    runs-on: ubuntu-24.04
+    strategy:
+      fail-fast: false
+      matrix:
+        loader: [fabric, forge]
+        mc:
+          - { version: '1.20.1', java: '21', gradle: '8.10.2' }
+          - { version: '1.21.1', java: '21', gradle: '8.10.2' }
+          - { version: '26.1.2', java: '25', gradle: '9.6.0' }
+          - { version: '26.2', java: '25', gradle: '9.6.0' }
+          - { version: '26.3', java: '25', gradle: '9.6.0' }
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-java@v5
+        with:
+          distribution: temurin
+          java-version: ${{ matrix.mc.java }}
+      - uses: gradle/actions/setup-gradle@v4
+        with:
+          gradle-version: ${{ matrix.mc.gradle }}
+      - run: gradle -p integrations -Ploader=${{ matrix.loader }} -PmcVersion=${{ matrix.mc.version }} -PreleaseVersion="${{ inputs.version || '0.1.0' }}" :${{ matrix.loader }}:build
+      - name: Audit Fabric hooks during server bootstrap (no world startup)
+        if: matrix.loader == 'fabric'
+        run: gradle -p integrations -Ploader=fabric -PmcVersion=${{ matrix.mc.version }} -PreleaseVersion="${{ inputs.version || '0.1.0' }}" -PverifyMixins=true :fabric:runServer
+      - uses: actions/upload-artifact@v4
+        with:
+          name: server-${{ matrix.loader }}-${{ matrix.mc.version }}
+          path: integrations/${{ matrix.loader }}/build/libs/scopenet-${{ matrix.loader }}-${{ matrix.mc.version }}-*.jar
+          if-no-files-found: error