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/expected/0714-modules-json-reader.stdout

@@ -0,0 +1,43 @@
+root-is-object: ok
+member-count: ok
+key-order-0: ok
+string-plain: ok
+string-escaped: ok
+array-len: ok
+array-pos: ok
+array-neg: ok
+bool-value: ok
+null-value: ok
+nested-pair: ok
+plain-is-view: ok
+escaped-allocated: ok
+round-trip: ok
+ws-count: ok
+ws-first: ok
+ws-last: ok
+empty-array: ok
+empty-object: ok
+uni-len: ok
+uni-A: ok
+uni-e1: ok
+uni-e2: ok
+uni-i0: ok
+uni-i1: ok
+uni-i2: ok
+uni-i3: ok
+err-truncated: ok
+err-bad-escape: ok
+err-trailing-junk: ok
+err-bad-token: ok
+err-fraction: ok
+err-leading-zero: ok
+err-overflow: ok
+err-unterminated: ok
+err-raw-tab: ok
+err-raw-lf: ok
+err-raw-nul: ok
+esc-ctrl-len: ok
+esc-tab: ok
+esc-lf: ok
+esc-u: ok
+=== DONE ===