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, 9 insertions, 12 deletions

diff --git a/crates/shirabe/src/command/remove_command.rs b/crates/shirabe/src/command/remove_command.rs
index 77deaf14..e89e9535 100644
--- a/crates/shirabe/src/command/remove_command.rs
+++ b/crates/shirabe/src/command/remove_command.rs
@@ -193,12 +193,10 @@ impl Command for RemoveCommand {
                 .as_bool()
                 .unwrap_or(false)
         {
-            return Err(anyhow::anyhow!(InvalidArgumentException(
-                shirabe_php_shim::InvalidArgumentException {
-                    message: "Not enough arguments (missing: \"packages\").".to_string(),
-                    code: 0,
-                }
-            )));
+            return Err(InvalidArgumentException::new(
+                "Not enough arguments (missing: \"packages\").".to_string(),
+            )
+            .into());
         }
 
         let mut packages: Vec<String> = input
@@ -224,12 +222,11 @@ impl Command for RemoveCommand {
                 let locker = composer.get_locker().clone();
                 let mut locker = locker.borrow_mut();
                 if !locker.is_locked() {
-                    return Err(anyhow::anyhow!(UnexpectedValueException {
-                        message:
-                            "A valid composer.lock file is required to run this command with --unused"
-                                .to_string(),
-                        code: 0,
-                    }));
+                    return Err(UnexpectedValueException::new(
+                        "A valid composer.lock file is required to run this command with --unused"
+                            .to_string(),
+                    )
+                    .into());
                 }
             }