Migrate scrabble module to Conductor

[Shrey5132]

Description

Fixes #782

Migrates the scrabble module to be Conductor-ready. scrabble has no tab/visualization component, so this is scoped entirely to src/bundles/scrabble/.

Unlike repeat/binary_tree/midi, scrabble exports four static word/letter lists, not functions - there's nothing for the usual exportedNames/@moduleMethod closure path to wrap. index.ts is now a BaseModulePlugin subclass that pushes all four exports in an initialise() override, built as real DataType.ARRAYs via array_make/array_set.

DataType.OPAQUE was the initial choice here (see review history) - IDataHandler.array_make has no bulk constructor, so populating an array is one array_set call per element, and scrabble_words alone is 172,820 entries. That looked prohibitive on paper. It wasn't measured, though, and the actual cost (via @sourceacademy/modules-testplugin's TestDataHandler) is ~246ms one-time for both scrabble_words and the nested scrabble_letters combined - negligible at module-load time, and a module's evaluator runs in the same execution context (the Runner), so there's no postMessage boundary inflating that further in production. opaque_make stays the right call for genuinely opaque payloads (e.g. binary_tree's node values, rune's whole Rune object) - the difference is scrabble's data isn't opaque at all, it's a plain word list, so wrapping it that way just cost students print/indexing/iteration for no real reason.

This also follows source-academy/py-slang#217's module-interop fixes and the resulting team decision that Python lists / JS arrays should be the only built-in data structure modules hand back, rather than reaching for opaque_make on anything compound.

functions.ts is untouched - it's pure data derivation (map/filter over the word list), nothing conductor-specific about it.

Unrelated bug fixed along the way

The existing scrabble_words matches snapshot / scrabble_letters matches snapshot tests hung vitest indefinitely - confirmed via bisection against repeat's suite (clean, 1.2s) and this module's new test in isolation via .only (clean, 2.76s). Snapshotting a 172,820-entry array (and the nested scrabble_letters) produced a 2.1M-line .snap file that vitest's serializer choked on. Dropped those two tests and deleted the stale snapshot file; the existing index spot-checks (scrabble_words[12], scrabble_letters[100000]) already cover the full arrays cheaply, and the _tiny variants (~1,728 entries) still get proper snapshots (regenerated, 2 written).

Testing

• yarn workspace @sourceacademy/bundle-scrabble run tsc - passes
• yarn workspace @sourceacademy/bundle-scrabble run lint - passes
• yarn workspace @sourceacademy/bundle-scrabble run test - 5/5 passing, against @sourceacademy/modules-testplugin's TestDataHandler
• yarn workspace @sourceacademy/bundle-scrabble run build - produces build/bundles/scrabble.js

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[gemini-code-assist]

Code Review

This pull request refactors the scrabble bundle to export a ScrabbleModulePlugin extending BaseModulePlugin instead of directly exporting the word lists. The word lists are now exposed as opaque values asynchronously during initialization. Additionally, snapshot tests for the full-sized word lists were removed to prevent test runner hangs, and a new test was added to verify the plugin's initialization behavior. Feedback is provided to optimize the initialization performance by executing the asynchronous opaque_make calls concurrently using Promise.all instead of sequentially.

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