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.
Add examples/1223-ffi-extern-fn.sx — binds libc 'abs' via bare 'extern'
(sx name = C symbol, no rename). Hand-authored expected/ captures the
SUCCESS output (abs(-7)=7 / abs(42)=42, exit 0).
RED: 1223 is the sole corpus failure (634 ran, 1 failed) — it parses
then errors at sema ('body produces no value') because lowering does
not yet route extern fns through declareExtern. Phase 1.1 wires the
lowering and turns this green.
xfail commit per the cadence rule (no commit both adds a test and makes
it pass).
