sound: fix lint errors on conductor-migration

[Akshay-2007-1]

Fixes both problems blocking the conductor-migration deploy after #796 merged.

1. Lint errors (@martin-henz's report)

@sourceacademy/throw-runtime-error doesn't recognize EvaluatorParameterTypeError as assignable to RuntimeSourceError - same known gap already worked around in midi. 6 call sites across functions.ts/index.ts hit this.

Separately, conductorToSound's invalid() helper was throwing a plain Error, not a Conductor error type at all - a real bug, not just a lint gap, since it would bypass proper student-facing error formatting.

What changed:

• Added the same eslint-disable-next-line @sourceacademy/throw-runtime-error + explanatory comment midi already uses, at each of the 6 EvaluatorParameterTypeError call sites.
• Fixed invalid() to throw EvaluatorRuntimeError instead of a plain Error, and inlined the three call sites (the indirection through a helper function was itself what kept the linter from recognizing a type it accepts fine when thrown directly).
• Left the constructor's soundChannel wiring guard as a plain Error with a disable comment - a genuine internal precondition (Conductor host failed to provide the channel), never reachable from student code.
• Fixed two @stylistic/member-delimiter-style warnings in recording.test.ts.

Verified clean: lint, tsc, all 64 tests pass.

2. Docs build failure (twoslash type errors)

#796 removed AudioPlayed/SoundModuleState entirely (the old js-slang moduleContexts.sound.state pattern doesn't apply to Conductor-based modules) and reshaped Sound from a Pair to {leftWave, rightWave, duration}. Several doc pages' embedded, type-checked code samples still referenced the old shapes, failing the docs build's twoslash validation:

• 2-bundle/4-conventions/3-errors.md: make_sound sample used pair() from js-slang/dist/stdlib/list against the old Sound type - rewritten to return the real {leftWave, rightWave, duration} shape.
• 5-advanced/context.md, 3-tabs/1-overview.md, 3-tabs/3-editing.md: all three used sound as their example bundle for the general js-slang module context / getModuleState pattern, referencing AudioPlayed/SoundModuleState which no longer exist at all. Swapped to curve, which still legitimately uses this pattern (sound moved to Conductor's own channel-based state instead) - reused curve's actual CurveModuleState/drawnCurves shape and the real Curve tab's own getModuleState usage as the reference.

Verified the two rewritten samples against a real tsc --strict run (not just eyeballing) - both type-check clean.

4-testing/4-unit/3-mock.md and 2-bundle/1-overview/1-overview.md also reference bundle-sound but only via imports/calls that stay valid regardless of Sound's internal shape (no destructuring assuming the old pair shape) - left as-is, not build-blocking, though mock.md's AudioContext example is now semantically stale (play() no longer touches AudioContext directly) and could use a follow-up pass.

[gemini-code-assist]

Caution

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