Parser: release non-global semantic state

Parser: release non-global semantic state

Allocate non-global scopes, local variables, variable tree nodes, references,
and declaration arrays from the compilation pool.  The global scope and its
symbol table remain persistent for runtime lookup and later compilation.

Build closure-index arrays temporarily, then copy the finalized indexes into
VM-owned storage referenced by each lambda.  Preserve declaration-origin type
without retaining pointers to released block scopes.