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/0740-modules-flat-same-name-ufcs-typing/a.sx

@@ -0,0 +1,6 @@
+#import "modules/std.sx";
+// a.sx authors `tag` returning a string; imported first → first-wins winner.
+// `show_a`'s `v.tag()` is the caller's OWN author (own == winner → existing UFCS
+// path, byte-for-byte unchanged): typed AND dispatched as a.tag (string).
+tag :: ufcs (x: i64) -> string { return "a-string"; }
+show_a :: () { v : i64 = 10; print("a: v.tag() = {}\n", v.tag()); }

examples/modules/0740-modules-flat-same-name-ufcs-typing/b.sx

@@ -0,0 +1,7 @@
+#import "modules/std.sx";
+// b.sx authors its OWN `tag` returning i64. `show_b`'s `v.tag()` must be both
+// dispatched AND typed as b.tag (i64 = 110), not the first-wins winner from a.sx
+// (string). `print` types each arg from the call plan, so a mistype here boxes
+// the i64 as a string pointer → segfault before the fix.
+tag :: ufcs (x: i64) -> i64 { return x + 100; }
+show_b :: () { v : i64 = 10; print("b: v.tag() = {}\n", v.tag()); }