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/modules/0732-modules-flat-same-name-ufcs/b.sx

@@ -0,0 +1,4 @@
+// b.sx authors its OWN `bump` adding 100. `from_b`'s `v.bump()` must dispatch
+// b.sx's author (+100 → 110), not the first-wins winner from a.sx (+1).
+bump   :: ufcs (x: i64) -> i64 { return x + 100; }
+from_b_ufcs :: () -> i64 { v : i64 = 10; return v.bump(); }