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/0813-modules-same-name-error-set-lambda-own-wins/dep.sx

@@ -0,0 +1,11 @@
+// A flat-imported module authors its OWN `IoErr { Net }`. The importing file
+// (`main`) ALSO authors an `IoErr` AND uses it as a closure-literal return
+// annotation (`-> !IoErr`); main's author must win THERE too (own-wins),
+// while this module's `IoErr` stays a DISTINCT nominal used by `dep_err`.
+// The tag sets are disjoint, so binding the wrong `IoErr` is a hard compile
+// error (`Net` is not in main's `{ Disk }`, and vice-versa).
+IoErr :: error { Net }
+
+dep_err :: () -> IoErr {
+    return error.Net;
+}