Completes the invoke→cek-call migration across all spec .sx files:
- adapter-sx.sx: map/filter/for-each in aser wire format
- adapter-dom.sx: island render update-fn
- engine.sx: fetch transform callback
- test-cek-reactive.sx: disposal test
Only async-invoke (adapter-async.sx) remains — separate async pattern.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
test-cek-reactive.sx: 9 tests across 4 suites — deref pass-through,
signal without reactive-reset, reactive-reset shift with continuation
capture, scope disposal cleanup. run_cek_reactive_tests.py: new runner
loading signals+frames+cek. Both test runners override sx_ref.eval_expr
back to tree-walk so interpreted .sx uses tree-walk internally.
Plan page added to sx-docs.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
