Email attachment builder: typed-array helper + worker test

[guybedford]

This adopts the ts-gen typed-array builder cleanups in the regenerated worker/src/email.rs. The dictionary helpers for EmailAttachment.content now expose a generic *_with_typed_array<T: ::js_sys::TypedArray> shape, plus the keyword-safe type_ getter, the deduped set_disposition, and trimmed JSDoc output.

// before
EmailAttachment::new_attachment_with_js_value(content: &Object, filename: &str, r#type: &str)

// after
EmailAttachment::new_attachment_with_typed_array<T: ::js_sys::TypedArray>(
    content: &T,
    filename: &str,
    r#type: &str,
)

The submodule bump pulls in the ts-gen changes from wasm-bindgen/ts-gen#15.

A new end-to-end worker test exercises the regenerated builder against the live email binding:

• test/src/send_email.rs adds a structured-with-attachment scenario that builds a Uint8Array, constructs the attachment via EmailAttachment::new_attachment_with_typed_array, and attaches it to the structured SendEmailBuilder.
• test/tests/send_email.spec.ts adds a matching vitest case.

Tests

• cargo +stable check -p worker-sandbox --target wasm32-unknown-unknown
• Existing send_email vitest cases still pass; new typed-array scenario added.

Remaining follow-ups

These belong upstream in ts-gen, but are worth listing here so the workers-rs side is regenerated when they land:

• Strip undefined/void arms in the union LUB so contentId?: string | undefined becomes Option<String> and the dead set_content_id_with_undefined setter overload disappears.
• Make the Returns: JSDoc rendering JSDoc-aware (backtick the braced {T}, leave prose untouched).

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 2 untouched benchmarks

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_{Comparing feat/email-typed-array-attachment-builder (f83f5e8) with main (7ad7139)}