Release 0.9a: Move ng to main, modernize PHP 8.1+ client, update documentation and add Gitea workflow

.gitea/workflows/release-test.yaml

@@ -0,0 +1,40 @@
+name: Release PHP Validity Check
+
+on:
+  release:
+    types: [published, created]
+  push:
+    branches: [master, main]
+    tags: ['v*']
+  pull_request:
+    branches: [master, main]
+
+jobs:
+  php-validity:
+    name: PHP Validity (PHP ${{ matrix.php-version }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        php-version: ['8.1', '8.2', '8.3', '8.4']
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-version }}
+          extensions: curl, json
+          coverage: none
+
+      - name: PHP Syntax Check (Lint)
+        run: |
+          php -l ninjamail.class.php
+          php -l test_all.php
+          php -l tests/test_validity.php
+
+      - name: Run PHP Validity & Type Tests (Offline - No API Calls)
+        run: |
+          php tests/test_validity.php