[WIP] Update JS lingo script for parity with Python

[Copilot]

JS Lingo Script Parity Implementation

Phase 1: Analysis & Setup

• Understand Python lingo.py implementation
• Understand current JS markup.js implementation
• Identify missing types and functions
• Set up test infrastructure (package.json, playwright config)

Phase 2: Type System Updates

• Update return value formatting to match Python (wrap primitives in {value, type} dicts)
• Add support for list types with element_type
• Fix type checking for all operations

Phase 3: Missing Functions Implementation

• Add comparison operators (eq, ne, lt, le, gt, ge)
• Add int function with string/base support
• Add float and round functions
• Add str and join functions
• Add math functions (floordiv, mod, min, max, abs)
• Add sequence functions (len, range, slice, any, all, sum, sorted)
• Add sequence ops (map, filter, dropwhile, takewhile, reversed, accumulate, reduce)
• Fix datetime handling and current.weekday
• Fix random.randint

Phase 4: Testing

• Create browser2/js/tests directory
• Set up playwright test infrastructure
• Create browser2.spec.js with tests for each test_data file
• Add tests for hello_world_test_data.json
• Add tests for basic_math_test_data.json
• Add tests for all_param_types_test_data.json
• Add tests for branch_example_test_data.json
• Add tests for switch_example_test_data.json

Phase 5: Validation

• Run all tests and fix failures
• Verify parity with Python implementation
• Document any known gaps

Original prompt

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This section details on the original issue you should resolve

<issue_title>JS Lingo script parity with Python</issue_title>
<issue_description>The lingo script spec is a scripting language embedded in json/yaml and executed by interpreters in javascript and python.

The current implementation is on the dev branch, the documentation for it is in the readme and other files in ./docs. There are examples in src/mspec/data/lingo/pages and src/mspec/data/lingo/scripts for the page-beta-1 and script-beta-1 variations of the spec. The python interpreter is in src/mspec/lingo.py. The python interpreter is tested against the test scripts in tests/test_markup.py. These tests iterate over the *_test_data.json specs in src/mspec/data/lingo/scripts to confirm that given sets of input params return the expected result.

There's been a lot of changes to the scripting language in the python interpreter and we'd like to update the JS interpreter to match. The new spec is outlined in the ./docs/LINGO_* documents. Please update the JS interpreter to have parity in types and functions. The current JS interpreter is in browser2/js/src. It can be tested by running the dev server with ./server.py and then running the playwright tests in this folder.

requirements

• add support for all types that are defined in the spec
• add support for all functions defined in the spec
• add tests for each test file in src/mspec/data/lingo/scripts in browser2/js/tests/browser2.spec.js, they should test that default params return expected result. This is a big ticket so it's fine if not all tests are passing in first PR
• make a branch off of dev and submit a PR back to the dev branch.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes JS Lingo script parity with Python #20

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