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/expected/1652-platform-asm-indirect-mem.ir

@@ -0,0 +1,18 @@
+
+; Function Attrs: nounwind
+define internal i64 @poke() #0 {
+entry:
+  %alloca = alloca i64, align 8
+  store i64 0, ptr %alloca, align 8
+  call void asm sideeffect "        mov x9, #42\0A        str x9, ${0}\0A", "=*m,~{x9}"(ptr elementtype(i64) %alloca)
+  %load = load i64, ptr %alloca, align 8
+  ret i64 %load
+}
+
+; Function Attrs: nounwind
+define i32 @main() #0 {
+entry:
+  %call = call i64 @poke()
+  %ca.tr = trunc i64 %call to i32
+  ret i32 %ca.tr
+}