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/0792-modules-same-name-const-struct-field-dim/a.sx

@@ -0,0 +1,5 @@
+// Module A authors `K :: 2` and a struct `Box` whose array field is dimensioned
+// by A's `K`. `size_of(Box)` folds the field dimension against A's `K` (= 2).
+K :: 2;
+Box :: struct { arr: [K]u8; }
+a_sz :: () -> i64 { return size_of(Box); }

examples/modules/0792-modules-same-name-const-struct-field-dim/b.sx

@@ -0,0 +1,6 @@
+// Module B authors a DIFFERENT same-name `K :: 7` and same-name struct `Box`.
+// `size_of(Box)` folds the field dimension against B's `K` (= 7), so the layout
+// differs from A's — never collapsed to a global last-wins `K`.
+K :: 7;
+Box :: struct { arr: [K]u8; }
+b_sz :: () -> i64 { return size_of(Box); }