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/0779-modules-qualified-generic-static-method-author/a.sx

@@ -0,0 +1,8 @@
+// Author A's generic `Box` — one i64 field (size 8). Its `make` sets only `x`.
+Box :: struct($T: Type) {
+    x: T;
+
+    make :: (value: T) -> Box(T) {
+        .{ x = value }
+    }
+}

examples/modules/0779-modules-qualified-generic-static-method-author/b.sx

@@ -0,0 +1,11 @@
+// Author B's generic `Box` — two i64 fields (size 16). Same template NAME as
+// A's, different layout AND different `make` (sets `y = value + 100`). The
+// qualified static head must select by namespace author for both.
+Box :: struct($T: Type) {
+    x: T;
+    y: T;
+
+    make :: (value: T) -> Box(T) {
+        .{ x = value, y = value + 100 }
+    }
+}