Rename and rebrand to mayr_validator with new structure

Renamed package from mayr_dart_validator to mayr_validator, updated all references, and restructured library and example files. Added comprehensive DESIGN.md, enhanced README with usage and features, introduced GitHub Actions workflows for CI and publishing, and updated pubspec.yaml with new metadata. Old files and tests were renamed or removed to match the new package structure.

Create LICENSE

Author: YoungMayor

.github/workflows/ci.yaml

@@ -0,0 +1,37 @@
+name: ci
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+on:
+  pull_request:
+    branches:
+      - main
+
+  # push:
+  #   branches:
+  #     - main
+
+jobs:
+  ci_checks:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: 📚 Git Checkout
+        uses: actions/checkout@v4
+
+      - name: 🐦 Setup Flutter
+        uses: subosito/flutter-action@v2
+
+      - name: 📦 Install Dependencies
+        run: flutter pub get
+
+      - name: Run tests
+        run: flutter test
+
+      - name: ✨ Format
+        run: dart format --set-exit-if-changed .
+
+      - name: 🔍 Analyze
+        run: dart analyze --fatal-warnings .

.github/workflows/publish.yml

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+# .github/workflows/publish.yml
+name: Publish to pub.dev
+
+on:
+  push:
+    tags:
+    # must align with the tag-pattern configured on pub.dev, often just replace
+      # {{version}} with [0-9]+.[0-9]+.[0-9]+
+    - 'v[0-9]+.[0-9]+.[0-9]+' # tag-pattern on pub.dev: 'v{{version}}'
+    # If you prefer tags like '1.2.3', without the 'v' prefix, then use:
+    # - '[0-9]+.[0-9]+.[0-9]+' # tag-pattern on pub.dev: '{{version}}'
+    # If your repository contains multiple packages consider a pattern like:
+    # - 'my_package_name-v[0-9]+.[0-9]+.[0-9]+'
+
+# Publish using the reusable workflow from dart-lang.
+jobs:
+  publish:
+    permissions:
+      id-token: write # Required for authentication using OIDC
+    uses: dart-lang/setup-dart/.github/workflows/publish.yml@v1
+    # with:
+    #   working-directory: path/to/package/within/repository