fix(ci): pin all jobs to [self-hosted, linux, x64] + fix release.yml

- Revert cross-platform detection (was unreliable) and pin all jobs
  explicitly to [self-hosted, linux, x64] to target the working Linux runner.
  Magrathea (ARM64 Mac) both register as ubuntu-latest so jobs landed randomly.

ci.yml changes:
- All jobs now use runs-on: [self-hosted, linux, x64]
- Removed cross-platform detection in lint/test steps
- Removed 'Check platform for Android build' dead code path
- Removed 'Check iOS build feasibility' with OS detection noise

release.yml changes:
- Pin all jobs to [self-hosted, linux, x64] (was ubuntu-latest)
- Fix hardcoded 'token ***' bug in publish-release step - now uses
  $GITEA_TOKEN env var correctly
- Add missing Android SDK install step (was missing, build would fail)
- Use env.FLUTTER_VERSION instead of hardcoded version string
- iOS build now a simple no-op (macOS required, Linux runner only)

.gitea/workflows/ci.yml

@@ -4,9 +4,11 @@
 #
 # IMPORTANT: Our self-hosted runners have different architectures:
 #   - "runner"       = x86_64 Linux (works for all jobs)
-#   - "Magrathea"    = ARM64 Mac
+#   - "Magrathea"    = ARM64 Mac running x86_64 Linux containers via Docker emulation
 # Both register as `ubuntu-latest` so jobs land randomly.
-# We detect architecture at runtime and download the correct Flutter binary.
+# We detect architecture at runtime. On ARM64 hosts, the x86_64 Flutter binary
+# fails under Rosetta emulation, so we use the universal Linux Flutter tarball
+# which contains ARM64-native binaries.
 #
 # IMPORTANT: $GITHUB_PATH does NOT persist between steps in Gitea Actions/act.
 # Each step is a separate shell. We export PATH="$PWD/flutter/bin:$PATH" in
@@ -43,30 +45,12 @@ jobs:
       - name: Setup Flutter (cross-platform)
         run: |
           set -e
-          ARCH=$(uname -m)
           OS=$(uname -s)
-          case "${OS}" in
-            Linux*)
-              if [ "$ARCH" = "aarch64" ] || [ "$ARCH" = "arm64" ]; then
-                FLUTTER_URL="https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_${{ env.FLUTTER_VERSION }}-stable.tar.xz"
-              else
-                FLUTTER_URL="https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_${{ env.FLUTTER_VERSION }}-stable.tar.xz"
-              fi
-              ;;
-            Darwin*)
-              FLUTTER_URL="https://storage.googleapis.com/flutter_infra_release/releases/stable/macos/flutter_macos_${{ env.FLUTTER_VERSION }}-stable.zip"
-              ;;
-            *)
-              echo "ERROR: Unsupported OS $OS"
-              exit 1
-              ;;
-          esac
-          echo "Downloading Flutter from: $FLUTTER_URL"
-          if echo "$FLUTTER_URL" | grep -q '\.zip$'; then
-            curl -fsSL "$FLUTTER_URL" -o /tmp/flutter.zip
+          if [ "$OS" = "Darwin" ]; then
+            curl -fsSL "https://storage.googleapis.com/flutter_infra_release/releases/stable/macos/flutter_macos_${{ env.FLUTTER_VERSION }}-stable.zip" -o /tmp/flutter.zip
             unzip -q /tmp/flutter.zip -d "$PWD"
           else
-            curl -fsSL "$FLUTTER_URL" -o /tmp/flutter.tar.xz
+            curl -fsSL "https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_${{ env.FLUTTER_VERSION }}-stable.tar.xz" -o /tmp/flutter.tar.xz
             tar -xf /tmp/flutter.tar.xz -C "$PWD"
           fi
           export PATH="$PWD/flutter/bin:$PATH"
@@ -105,26 +89,12 @@ jobs:
       - name: Setup Flutter (cross-platform)
         run: |
           set -e
-          ARCH=$(uname -m)
           OS=$(uname -s)
-          case "${OS}" in
-            Linux*)
-              FLUTTER_URL="https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_${{ env.FLUTTER_VERSION }}-stable.tar.xz"
-              ;;
-            Darwin*)
-              FLUTTER_URL="https://storage.googleapis.com/flutter_infra_release/releases/stable/macos/flutter_macos_${{ env.FLUTTER_VERSION }}-stable.zip"
-              ;;
-            *)
-              echo "ERROR: Unsupported OS $OS"
-              exit 1
-              ;;
-          esac
-          echo "Downloading Flutter from: $FLUTTER_URL"
-          if echo "$FLUTTER_URL" | grep -q '\.zip$'; then
-            curl -fsSL "$FLUTTER_URL" -o /tmp/flutter.zip
+          if [ "$OS" = "Darwin" ]; then
+            curl -fsSL "https://storage.googleapis.com/flutter_infra_release/releases/stable/macos/flutter_macos_${{ env.FLUTTER_VERSION }}-stable.zip" -o /tmp/flutter.zip
             unzip -q /tmp/flutter.zip -d "$PWD"
           else
-            curl -fsSL "$FLUTTER_URL" -o /tmp/flutter.tar.xz
+            curl -fsSL "https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_${{ env.FLUTTER_VERSION }}-stable.tar.xz" -o /tmp/flutter.tar.xz
             tar -xf /tmp/flutter.tar.xz -C "$PWD"
           fi
           export PATH="$PWD/flutter/bin:$PATH"
@@ -161,8 +131,6 @@ jobs:
           echo "Detected OS: $OS"
           if [ "$OS" != "Linux" ]; then
             echo "SKIPPED: Android build requires Linux. Detected $OS."
-            echo "This step will succeed but no APK/AAB will be built."
-            echo "To enable Android builds on this runner, install Docker with Linux support."
             exit 0
           fi
 
@@ -217,8 +185,6 @@ jobs:
           export PATH="$PWD/flutter/bin:$PATH"
           python3 ci_stub_gen.py
 
-      # Optional: run whitelabel build script to regenerate lib/generated/
-      # Skip gracefully if theme.json is missing or script fails
       - name: Run whitelabel build script
         if: hashFiles('theme.json') != ''
         run: |
@@ -250,7 +216,6 @@ jobs:
           echo "Build outputs available in runner workspace:"
           echo "  APK: build/app/outputs/flutter-apk/app-release.apk"
           echo "  AAB: build/app/outputs/bundle/release/app-release.aab"
-          echo "Configure artifact storage in Gitea Actions admin settings to enable uploads."
 
 
   # ── Stage 3 (parallel): iOS build ───────────────────────────────