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, 5 insertions, 11 deletions

diff --git a/crates/shirabe/src/command/licenses_command.rs b/crates/shirabe/src/command/licenses_command.rs
index 41e9ba90..1b2ec6b6 100644
--- a/crates/shirabe/src/command/licenses_command.rs
+++ b/crates/shirabe/src/command/licenses_command.rs
@@ -128,10 +128,7 @@ impl Command for LicensesCommand {
             let locker = composer.get_locker().clone();
             let mut locker = locker.borrow_mut();
             if !locker.is_locked() {
-                return Err(UnexpectedValueException {
-                    message: "Valid composer.json and composer.lock files are required to run this command with --locked".to_string(),
-                    code: 0,
-                }.into());
+                return Err(UnexpectedValueException::new("Valid composer.json and composer.lock files are required to run this command with --locked".to_string()).into());
             }
             let no_dev = input
                 .borrow()
@@ -314,13 +311,10 @@ impl Command for LicensesCommand {
                 );
             }
             _ => {
-                return Err(RuntimeException {
-                    message: format!(
-                        "Unsupported format \"{}\".  See help for supported formats.",
-                        format
-                    ),
-                    code: 0,
-                }
+                return Err(RuntimeException::new(format!(
+                    "Unsupported format \"{}\".  See help for supported formats.",
+                    format
+                ))
                 .into());
             }
         }