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, 12 insertions, 11 deletions

diff --git a/crates/shirabe/tests/json/json_file_test.rs b/crates/shirabe/tests/json/json_file_test.rs
index 49ac1605..a20e7234 100644
--- a/crates/shirabe/tests/json/json_file_test.rs
+++ b/crates/shirabe/tests/json/json_file_test.rs
@@ -3,6 +3,7 @@
 use indexmap::IndexMap;
 use shirabe::json::{JsonEncodeOptions, JsonFile, JsonValidationException};
 use shirabe_external_packages::seld::json_lint::ParsingException;
+use shirabe_php_shim::Catch as _;
 use shirabe_php_shim::PhpMixed;
 
 /// ref: JsonFileTest::expectParseException
@@ -269,14 +270,14 @@ fn test_schema_validation_error() {
     let err = json
         .validate_schema(JsonFile::STRICT_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(expected_message, e.get_message());
     assert!(e.get_errors().contains(&expected_error));
 
     let err = json
         .validate_schema(JsonFile::LAX_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(expected_message, e.get_message());
     assert!(e.get_errors().contains(&expected_error));
 }
@@ -298,7 +299,7 @@ fn test_schema_validation_lax_additional_properties() {
     let err = json
         .validate_schema(JsonFile::STRICT_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(
         format!("\"{}\" does not match the expected JSON schema", file),
         e.get_message()
@@ -327,7 +328,7 @@ fn test_schema_validation_lax_required() {
     let err = json
         .validate_schema(JsonFile::STRICT_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(expected_message, e.get_message());
     let errors = e.get_errors();
     assert!(errors.contains(&"name : \"name\" is a required property".to_string()));
@@ -338,7 +339,7 @@ fn test_schema_validation_lax_required() {
     let err = json
         .validate_schema(JsonFile::STRICT_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(expected_message, e.get_message());
     assert_eq!(
         &vec!["description : \"description\" is a required property".to_string()],
@@ -350,7 +351,7 @@ fn test_schema_validation_lax_required() {
     let err = json
         .validate_schema(JsonFile::STRICT_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(expected_message, e.get_message());
     assert_eq!(
         &vec!["name : \"name\" is a required property".to_string()],
@@ -362,7 +363,7 @@ fn test_schema_validation_lax_required() {
     let err = json
         .validate_schema(JsonFile::STRICT_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(expected_message, e.get_message());
     let errors = e.get_errors();
     assert!(errors.contains(&"name : \"name\" is a required property".to_string()));
@@ -373,7 +374,7 @@ fn test_schema_validation_lax_required() {
     let err = json
         .validate_schema(JsonFile::STRICT_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(expected_message, e.get_message());
     let errors = e.get_errors();
     assert!(errors.contains(&"name : \"name\" is a required property".to_string()));
@@ -444,7 +445,7 @@ fn test_auth_schema_validation_with_custom_data_source() {
 
     let err = JsonFile::validate_json_schema("COMPOSER_AUTH", &json, JsonFile::AUTH_SCHEMA, None)
         .unwrap_err();
-    let e = err.downcast_ref::<JsonValidationException>().unwrap();
+    let e = err.catch::<JsonValidationException>().unwrap();
     assert_eq!(expected_message, e.get_message());
     assert_eq!(&vec![expected_error], e.get_errors());
 }
@@ -519,7 +520,7 @@ fn test_composer_lock_file_merge_conflict_complex() {
         std::fs::read_to_string(fixture_path("composer-lock-merge-conflict-complex.txt")).unwrap();
 
     let err = JsonFile::parse_json(Some(&data), Some("/path/to/composer.lock")).unwrap_err();
-    assert!(err.downcast_ref::<ParsingException>().is_some());
+    assert!(err.is_instanceof::<ParsingException>());
 }
 
 #[test]
@@ -531,7 +532,7 @@ fn test_composer_lock_file_merge_conflict_complex_crlf() {
     .unwrap();
 
     let err = JsonFile::parse_json(Some(&data), Some("/path/to/composer.lock")).unwrap_err();
-    assert!(err.downcast_ref::<ParsingException>().is_some());
+    assert!(err.is_instanceof::<ParsingException>());
 }
 
 #[test]