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>

CHANGELOG.md

@@ -2,6 +2,16 @@
 
 All notable changes to this project will be documented in this file.
 
+## [1.1.1] - 2026-02-28
+
+### Added
+
+- **PHPUnit test suite**: 64 unit tests covering `BlockRenderer`, `WidgetRenderer`, `NavWalker`, and `TemplateController` classes with 107 assertions. Uses PHPUnit 11 and Brain\Monkey for WordPress function mocking.
+- **Test infrastructure**: `WP_HTML_Tag_Processor` functional stub using DOMDocument for testing block renderer HTML manipulation outside WordPress. Empty stubs for `WP_Block` and `WP_Widget` type hints.
+- **Build pipeline integration**: Tests run automatically before every `npm run build` via `prebuild` hook (`composer exec -- phpunit`).
+- **CI test job**: New PHPUnit test step in Gitea CI workflow between lint and build-release. Tests must pass before release packages are built.
+- **Release package exclusions**: `tests/`, `phpunit.xml.dist`, and `.phpunit.cache/` excluded from release ZIP packages with verification step.
+
 ## [1.1.0] - 2026-02-28
 
 ### Added