Add PHPUnit test suite with 64 unit tests (v1.1.1)

PHPUnit 11 + Brain\Monkey for WordPress function mocking. Tests cover
BlockRenderer (28), WidgetRenderer (9), NavWalker (14), and
TemplateController (12). Includes functional WP_HTML_Tag_Processor stub,
CI test job between lint and build-release, prebuild hook gating npm
build on passing tests, and release package exclusions for test files.

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

README.md

@@ -62,20 +62,41 @@ Activate the theme in **Appearance > Themes** in the WordPress admin.
 
 | Command | Description |
 | --- | --- |
-| `npm run build` | Full production build (copy JS, compile SCSS, minify CSS) |
+| `npm run build` | Full production build (runs tests, copies JS, compiles SCSS, minifies CSS) |
+| `npm run test` | Run PHPUnit test suite |
 | `npm run dev` | Watch SCSS files and recompile on changes |
 | `npm run scss` | Compile SCSS only |
 | `npm run postcss` | Minify CSS with Autoprefixer and cssnano |
 | `composer install` | Install PHP dependencies (Twig) |
 
+### Testing
+
+The theme includes a PHPUnit test suite with 64 unit tests and 107 assertions covering the core PHP classes:
+
+- **BlockRenderer** -- All 8 render methods (table, button, buttons, image, search, quote, pullquote, list)
+- **WidgetRenderer** -- Card wrapping, heading downgrade, class extraction
+- **NavWalker** -- Tree building, active item detection, orphan handling
+- **TemplateController** -- Template resolution for all page types
+
+Tests use [Brain\Monkey](https://brain-wp.github.io/BrainMonkey/) for WordPress function mocking and a functional `WP_HTML_Tag_Processor` stub.
+
+```bash
+# Run tests
+composer exec -- phpunit
+
+# Tests also run automatically before every build
+npm run build
+```
+
 ### Build Pipeline
 
-1. `copy:js` -- Copy Bootstrap JS bundle from `node_modules` to `assets/js/`
-2. `copy:theme-js` -- Copy theme JS (dark-mode.js) from `src/js/` to `assets/js/`
-3. `copy:icons` -- Copy Bootstrap Icons font files (`.woff`, `.woff2`) to `assets/fonts/`
-4. `scss` -- Compile SCSS (`src/scss/`) to CSS (`assets/css/`)
-5. `scss:rtl` -- Compile RTL stylesheet (`assets/css/rtl.css`)
-6. `postcss` -- Autoprefixer + cssnano minification to `assets/css/style.min.css`
+1. `test` -- Run PHPUnit test suite (automatic via `prebuild` hook)
+2. `copy:js` -- Copy Bootstrap JS bundle from `node_modules` to `assets/js/`
+3. `copy:theme-js` -- Copy theme JS (dark-mode.js) from `src/js/` to `assets/js/`
+4. `copy:icons` -- Copy Bootstrap Icons font files (`.woff`, `.woff2`) to `assets/fonts/`
+5. `scss` -- Compile SCSS (`src/scss/`) to CSS (`assets/css/`)
+6. `scss:rtl` -- Compile RTL stylesheet (`assets/css/rtl.css`)
+7. `postcss` -- Autoprefixer + cssnano minification to `assets/css/style.min.css`
 
 ## Architecture
 
@@ -140,6 +161,9 @@ wp-bootstrap/
 |   +-- js/           Source JavaScript
 |   +-- scss/         Source SCSS
 +-- styles/           Style variations (JSON)
++-- tests/
+|   +-- Stubs/        WordPress class stubs for testing
+|   +-- Unit/         PHPUnit test cases
 +-- templates/        FSE templates (HTML)
 +-- views/            Twig templates (Bootstrap 5 HTML)
 |   +-- base.html.twig
@@ -158,6 +182,7 @@ wp-bootstrap/
 - **Bootstrap 5.3+** CSS & JS (served locally)
 - **Dart Sass** for SCSS compilation
 - **PostCSS** with Autoprefixer and cssnano
+- **PHPUnit 11** with Brain\Monkey for WordPress function mocking
 
 ## License