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/1138-diagnostics-inline-for-non-integral-bound.sx

@@ -1,14 +0,0 @@
-// A NON-integral float (`4.5`) as an `inline for` range bound is a hard error:
-// the loop cursor must be a compile-time integer, so only an integral float
-// (`4.0`, `-2.0`) folds. Clean diagnostic + non-zero exit.
-//
-// Regression (F0.4 attempt 11, Agra ruling): range bounds are exempt from the
-// count negative-rejection (negatives are valid endpoints), but the
-// must-be-integer requirement still applies — `4.5` has no integer value.
-#import "modules/std.sx";
-
-main :: () {
-    s := 0;
-    inline for 0..4.5 (i) { s += i; }
-    print("unreachable: {}\n", s);
-}