- install BehaviorName: parse-set-cmd handles `element` separately so
`element's foo` after `set` invokes parse-poss rather than parse-expr,
fixing `set element's bar["count"] to X` inside behavior bodies
- parse-poss-tail ident case: call parse-poss (handles `[`) instead of
parse-prop-chain (does not) when next token is bracket-open
- hs-activate!: replace (handler el) with host-call-fn safe wrapper so
native OCaml "Undefined symbol" throws (which bypass SX guard frames)
are caught at the JS api_call_fn boundary rather than propagating
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>