feat: PSR-4 compatible cache structure for generated proxy files

[Copilot]

Cache files were generated under a convoluted _proxies/<original-relative-path>/<FQCN>.php layout that encoded the source file path rather than the class identity, making the cache directory unusable as a PSR-4 autoloader root and breaking correctness when classes are renamed or moved.

Proxy file path layout

Before: <cacheDir>/_proxies/src/Application/Main.php/Go/Tests/TestProject/Application/Main.php
After: <cacheDir>/Go/Tests/TestProject/Application/Main.php

Each proxy file now lives at a path derived purely from its FQCN, matching PSR-4 conventions.

ReflectionClass::getFileName() on proxy classes

With PSR-4 paths the proxy location no longer encodes the source path, so MagicConstantTransformer::resolveFileName() needed a new mechanism. Each generated proxy file now ends with a self-registration call:

// appended at the bottom of every generated proxy file:
\Go\Instrument\Transformer\MagicConstantTransformer::registerProxyFile(
    __FILE__,
    'src/Application/Main.php'   // relative to appDir; portable across environments
);

MagicConstantTransformer gains a static $proxyFileMap registry populated at include_once time, giving resolveFileName() an O(1) lookup before falling back to the existing cache-dir→app-dir path substitution for woven files.

DebugWeavingCommand proxy discovery

Replaced the hardcoded _proxies/ subdirectory scan with a recursive scan of the full cacheDir, filtering on the presence of \Go\Aop\Proxy in file content. The filter is broadened from implements \Go\Aop\Proxy to just \Go\Aop\Proxy to correctly match classes that implement additional interfaces before the proxy marker.

Cross-platform path handling

Both saveProxyToCache() and resolveFileName() normalize paths to forward slashes before computing relative paths so that Windows backslash paths from ReflectionClass::getFileName() are handled correctly.

Test/snapshot updates

• All *-woven.php snapshot files updated with new include_once AOP_CACHE_DIR . '/Ns/ClassName.php' paths.
• All *-proxy.php snapshot files updated with the registerProxyFile() footer.
• Regex patterns in WeavingTransformerTest fixed to escape the literal PHP concatenation dot (\.).