[CLI] Load WASM-backed WordPress plugins

[adamziel]

What it does

Adds an experimental --wasm-wordpress-plugin=<path> descriptor for loading WordPress plugins backed by PHP.wasm modules.

A descriptor wires together:

{
	"slug": "hello-wasm",
	"extension": {
		"name": "hello_wasm",
		"source": {
			"format": "manifest",
			"manifestUrl": "./dist/hello-wasm/manifest.json"
		}
	},
	"hooks": [
		{
			"type": "filter",
			"hook": "the_content",
			"callback": "hello_wasm_render_content"
		}
	]
}

The CLI loads the PHP.wasm extension before PHP starts, then writes an mu-plugin bootstrap that registers the declared WordPress hooks.

Rationale

The extension loader makes WASM modules available to PHP, but WordPress still needs a conventional PHP entry point for hooks. Installing a generated mu-plugin gives WASM-backed code a WordPress-native loading model: native functions/classes are exposed by the extension, and WordPress integration stays in PHP via add_action() / add_filter().

Implementation

• Adds readWasmWordPressPluginConfig() and expandWasmWordPressPluginArgs().
• Resolves local manifestUrl, baseUrl, and bootstrap paths relative to the descriptor file.
• Adds declarative action / filter hook registration with priority and acceptedArgs.
• Adds runtimePHPExtensions as the internal bridge from descriptor expansion to existing CLI PHP extension loading.
• Documents how to create, build, and load a WASM-backed WordPress plugin.
• Adds packages/php-wasm/compile-extension/examples/hello-dolly-wasm, a complete Hello Dolly-style example with C extension source, PHP bootstrap, descriptor, and run instructions.

Testing instructions

Run:

npx vitest run packages/playground/cli/tests/wasm-wordpress-plugins.spec.ts packages/playground/cli/tests/php-extensions.spec.ts --config packages/playground/cli/vite.config.ts

Also verified:

git diff --check

npx tsc -p packages/playground/cli/tsconfig.lib.json --noEmit --pretty false currently fails in this sparse checkout on missing workspace/build packages such as @php-wasm/node-8-4 and @wp-playground/blueprints.