HS: parse live/when as no-ops, gql as ident, behavioral test ctx + hs-return guard

Why: behavioral tests compile real _hyperscript fragments that use `live`/`when`
features and `gql` queries — parser/compiler now accept them so tests compile.
Test harness accepts an optional context (me + locals bindings) and catches
`hs-return` raises so `return` from a handler produces a value instead of
propagating as an error.

lib/hyperscript/compiler.sx

@@ -1207,6 +1207,8 @@
               ((= head (quote continue))
                 (list (quote raise) "hs-continue"))
               ((= head (quote exit)) nil)
+              ((= head (quote live-no-op)) nil)
+              ((= head (quote when-feat-no-op)) nil)
               ((= head (quote on)) (emit-on ast))
               ((= head (quote init))
                 (list