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, 3 insertions, 2 deletions

diff --git a/crates/shirabe/src/util/config_validator.rs b/crates/shirabe/src/util/config_validator.rs
index 9b6b292d..978a5cd2 100644
--- a/crates/shirabe/src/util/config_validator.rs
+++ b/crates/shirabe/src/util/config_validator.rs
@@ -10,6 +10,7 @@ use crate::package::loader::ValidatingArrayLoader;
 use indexmap::IndexMap;
 use serde::de::Error as _;
 use shirabe_external_packages::composer::pcre::Preg;
+use shirabe_php_shim::Catch as _;
 use shirabe_php_shim::{PhpMixed, php_regex};
 use shirabe_spdx_licenses::SpdxLicenses;
 
@@ -55,7 +56,7 @@ impl ConfigValidator {
         match schema_result {
             Ok(()) => {}
             Err(e) => {
-                if let Some(validation_e) = e.downcast_ref::<JsonValidationException>() {
+                if let Some(validation_e) = e.catch::<JsonValidationException>() {
                     for message in validation_e.get_errors() {
                         if lax_valid {
                             publish_errors.push(message.clone());
@@ -298,7 +299,7 @@ impl ConfigValidator {
         ) {
             Ok(_) => {}
             Err(e) => {
-                if let Some(invalid_e) = e.downcast_ref::<InvalidPackageException>() {
+                if let Some(invalid_e) = e.catch::<InvalidPackageException>() {
                     errors.extend_from_slice(invalid_e.get_errors());
                 }
             }