refactor(operation): replace OperationInterface with AnyOperation enum

Operations are only ever constructed by the dependency resolver, so a
plugin has no way to inject an implementation of its own and the set is
closed. Modelling it as an enum, like AnyPackage, removes the
OperationInterface trait together with its two parallel downcast
mechanisms (as_any() + downcast_ref, and as_*_operation()) and the
get_package() default method that panicked on UpdateOperation.

The PHP idiom `$op instanceof UpdateOperation ? getTargetPackage() :
getPackage()`, written out at six call sites, becomes
AnyOperation::get_target_package(). InstallationManager's three blocks
that matched on the type string and then recovered the type with
expect() collapse into exhaustive matches.

SolverOperation keeps only its TYPE constant; the shared
getOperationType()/__toString() implementations move to AnyOperation,
which also drops the five Self::TYPE.to_string() allocations.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/crates/shirabe/src/dependency_resolver/operation.rs b/crates/shirabe/src/dependency_resolver/operation.rs
index 720c5a0a..b0db094a 100644
--- a/crates/shirabe/src/dependency_resolver/operation.rs
+++ b/crates/shirabe/src/dependency_resolver/operation.rs
@@ -1,15 +1,15 @@
+pub mod any_operation;
 pub mod install_operation;
 pub mod mark_alias_installed_operation;
 pub mod mark_alias_uninstalled_operation;
-pub mod operation_interface;
 pub mod solver_operation;
 pub mod uninstall_operation;
 pub mod update_operation;
 
+pub use any_operation::*;
 pub use install_operation::*;
 pub use mark_alias_installed_operation::*;
 pub use mark_alias_uninstalled_operation::*;
-pub use operation_interface::*;
 pub use solver_operation::*;
 pub use uninstall_operation::*;
 pub use update_operation::*;