This addresses the deep nesting/recursion limits issue documented in
open-problems.md. The solution converts key parsing and compilation
paths from recursive to iterative approaches using explicit stacks.

Parser changes:
- Handle consecutive parentheses ((((1)))) iteratively
- Parse nested array literals [[[[1]]]] with a stack-based approach
- Add _parse_block_statement_iterative() for nested blocks {{{1;}}}
- Add _parse_nested_arrays() for nested array literals
- Add _continue_parsing_expression() for operators between parens
- Add _continue_binary_expression() for binary operators after parens

Compiler changes:
- Compile MemberExpression chains iteratively (for a[0][0][0]...)
- Use work stack for ArrayExpression compilation
- Handle BlockStatement compilation iteratively
- Make _compile_statement_for_value() drill through nested blocks

The approach was inspired by mquickjs's CPS-style parser, adapted to
Python with a simpler stack-based approach.

Tests now passing:
- test_deep_nested_parens
- test_deep_nested_braces
- test_deep_nested_arrays
- test_large_eval_parse_stack

Still xfail: test_deep_nested_regex_groups (regex parser)