test: group examples into per-category folders

Move examples/*.sx and their expected/ snapshots into per-category
subfolders (examples/<category>/...). Folder = leading filename token,
with ffi-objc/ffi-jni kept whole; filenames are unchanged. The corpus
runner and LSP sweep now discover each category's expected/ dir, while
issues/ stays flat. Example 1058's repo-root-relative companion import
is made file-relative. Path strings embedded in 164 snapshots were
regenerated (path-only changes). Test-layout docs in CLAUDE.md updated.

examples/platform/1615-platform-ios-sim-bundle.sx

@@ -0,0 +1,20 @@
+#import "modules/std.sx";
+#import "modules/build.sx";
+#import "modules/platform/bundle.sx";
+
+// Cross-compile regression for the iOS-simulator branch of
+// `platform.bundle`. On a host with the iPhoneSimulator SDK installed,
+// `sx build --target ios-sim` writes a `.app` with the iOS-shaped
+// Info.plist (UIDeviceFamily, LSRequiresIPhoneOS,
+// UIApplicationSceneManifest, DTPlatformName=iPhoneSimulator). Ad-hoc
+// codesign; no provisioning embed needed for the simulator.
+
+configure :: () abi(.compiler) {
+    opts := build_options();
+    opts.set_bundle_path("IosSimApp.app");
+    opts.set_bundle_id("co.example.iossim");
+    on_build(bundle_main);
+}
+#run configure();
+
+main :: () { print("ios-sim runtime main\n"); }