perf: move SwiftData cache and JSON encode off main thread during sync

- cacheStories() runs in Task.detached with a background ModelContext
- persistQuickCache() encodes 100 stories off-thread via Task.detached
- loadSectionSupplements() batches 5 parallel fetches into one sectionSupplement write

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/release.yml

@@ -0,0 +1,65 @@
+# Triggers on merge to main. Archives the app and exports an IPA.
+# TestFlight upload requires three secrets set in:
+#   Gitea → Repository Settings → Actions → Secrets
+#
+#   ASC_KEY_ID       — App Store Connect API key ID (e.g. ABC123DEFG)
+#   ASC_ISSUER_ID    — Issuer ID from App Store Connect → Users → API Keys
+#   ASC_PRIVATE_KEY  — Full contents of the downloaded .p8 file
+#
+# The runner Mac must have the distribution certificate and team K8BLMMR883
+# provisioning profile in its keychain (set up once in Xcode on that machine).
+name: Release
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  archive:
+    name: Archive & Export IPA
+    runs-on: [self-hosted, macos]
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Xcode version
+        run: xcodebuild -version
+
+      - name: Install XcodeGen
+        run: brew list xcodegen &>/dev/null || brew install xcodegen
+
+      - name: Generate Xcode project
+        run: xcodegen generate
+
+      - name: Archive (Release, device)
+        run: |
+          set -o pipefail
+          xcodebuild archive \
+            -project Jarvis.xcodeproj \
+            -scheme Jarvis \
+            -configuration Release \
+            -sdk iphoneos \
+            -archivePath build/Jarvis.xcarchive \
+            DEVELOPMENT_TEAM=K8BLMMR883
+
+      - name: Export IPA
+        run: |
+          set -o pipefail
+          xcodebuild -exportArchive \
+            -archivePath build/Jarvis.xcarchive \
+            -exportPath build/ipa \
+            -exportOptionsPlist ExportOptions.plist
+
+      - name: Upload to TestFlight
+        env:
+          ASC_KEY_ID: ${{ secrets.ASC_KEY_ID }}
+          ASC_ISSUER_ID: ${{ secrets.ASC_ISSUER_ID }}
+          ASC_PRIVATE_KEY: ${{ secrets.ASC_PRIVATE_KEY }}
+        run: |
+          echo "$ASC_PRIVATE_KEY" > /tmp/AuthKey_${ASC_KEY_ID}.p8
+          xcrun altool --upload-app \
+            --type ios \
+            --file build/ipa/Jarvis.ipa \
+            --apiKey "$ASC_KEY_ID" \
+            --apiIssuer "$ASC_ISSUER_ID"
+          rm -f /tmp/AuthKey_${ASC_KEY_ID}.p8