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/0796-modules-same-name-enum-own-wins/dep.sx

@@ -0,0 +1,6 @@
+// A flat-imported module authors its OWN `Dir { east; west }`. The importing file
+// (`main`) ALSO authors a `Dir` — its own author must win there (own-wins), while
+// this module's `Dir` stays a DISTINCT nominal type used by `dep_dir`. The variant
+// sets are disjoint, so a cross-binding to the wrong `Dir` is a hard compile error.
+Dir :: enum { east; west; }
+dep_dir :: () -> Dir { return .west; }