test: port Composer tests unblocked by mockall, add seams

Port 11 categories of previously-ignored Composer tests now reachable with
the mockall crate: DownloadManager, VCS/Perforce/File downloaders,
VersionSelector, PlatformRepository, Auditor, installer/FilesystemRepository,
RootPackageLoader, util auth/http, commands, and Cache.

Extract test seams additively on concrete structs as *Interface traits
(Runtime, HhvmDetector, VersionGuesser, RepositorySet, Perforce,
BinaryInstaller) plus mock-field seams (Cache, Filesystem); consumers take
trait objects. Mocks are defined locally in the test crates via
mockall::mock!, since automock-generated mocks are cfg(test)-gated and
invisible across the integration-test boundary.

dataProviders are ported in full; tests blocked by unported shims stay
#[ignore] with documented reasons rather than reduced or weakened.

Fix product bugs surfaced by the ports:
- util/github: use the exception code, not the HTTP status, for 401/403
- advisory: serialize empty audit maps as [] to match PHP json_encode
- repository/filesystem and downloader/file: fix RefCell double-borrow panics

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

1 files changed, 13 insertions, 12 deletions

diff --git a/crates/shirabe/src/downloader/file_downloader.rs b/crates/shirabe/src/downloader/file_downloader.rs
index b03db38..66f3390 100644
--- a/crates/shirabe/src/downloader/file_downloader.rs
+++ b/crates/shirabe/src/downloader/file_downloader.rs
@@ -124,18 +124,19 @@ impl FileDownloader {
         {
             // PHP: writeError('Running cache garbage collection', true, io_interface::VERY_VERBOSE)
             this.io.write_error("Running cache garbage collection");
-            cache.borrow_mut().gc(
-                this.config
-                    .borrow_mut()
-                    .get("cache-files-ttl")
-                    .as_int()
-                    .unwrap_or(0),
-                this.config
-                    .borrow_mut()
-                    .get("cache-files-maxsize")
-                    .as_int()
-                    .unwrap_or(0),
-            );
+            let ttl = this
+                .config
+                .borrow_mut()
+                .get("cache-files-ttl")
+                .as_int()
+                .unwrap_or(0);
+            let max_size = this
+                .config
+                .borrow_mut()
+                .get("cache-files-maxsize")
+                .as_int()
+                .unwrap_or(0);
+            cache.borrow_mut().gc(ttl, max_size);
         }
 
         this