feat(php-shim): give ported exceptions PHP's class hierarchy

Ported exceptions were flat structs reached with `downcast_ref`, so
Composer's `catch (\RuntimeException $e)` only matched the exact leaf
type and `get_class($e)` had nothing to report. Each exception now
embeds an instance of the class it extends and travels inside an
`AnyThrowable`; `Catch::catch`/`catch_mut` walk that chain, and
`PhpClass::php_class_name` yields the PHP FQCN.

Dropping the `std::error::Error` impls from the exception types leaves
`AnyThrowable` as the only route into an `anyhow::Error`, so the walk
cannot be bypassed. A `no_exception_downcast` linter catches the
`downcast::<X>()` calls that would now silently answer `None`.

Three sites change behavior as a result: the `TransportException`
exit-code override reaches `MaxFileSizeExceededException`, the
`catch (\LogicException)` in findSimilar() reaches its subclasses, and
rendered exception titles carry the real class name rather than a
guess. `get_class_err()` is no longer a `todo!()`, which re-enables
FilesystemRepositoryTest::testCorruptedRepositoryFile.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/crates/shirabe/tests/plugin/plugin_installer_test.rs b/crates/shirabe/tests/plugin/plugin_installer_test.rs
index 06cd2ce9..0c82a11a 100644
--- a/crates/shirabe/tests/plugin/plugin_installer_test.rs
+++ b/crates/shirabe/tests/plugin/plugin_installer_test.rs
@@ -31,6 +31,7 @@ use shirabe::util::r#loop::Loop;
 use shirabe::util::process_executor::ProcessExecutor;
 use shirabe_external_packages::symfony::console::output::output_interface::VERBOSITY_NORMAL;
 use shirabe_external_packages::symfony::process::PhpExecutableFinder;
+use shirabe_php_shim::Catch as _;
 use shirabe_php_shim::PhpMixed;
 use shirabe_semver::VersionParser;
 use tempfile::TempDir;
@@ -859,8 +860,7 @@ fn test_querying_with_invalid_capability_class_name_throws() {
                 ),
             };
         assert!(
-            err.downcast_ref::<shirabe_php_shim::UnexpectedValueException>()
-                .is_some(),
+            err.is_instanceof::<shirabe_php_shim::UnexpectedValueException>(),
             "expected UnexpectedValueException for {invalid_implementation_class_name:?}, got: {err}"
         );
         // PHP: ->expects($this->once())->method('getCapabilities').