perf: make encoding-browser 2x smaller

[ChALkeR]

No description provided.

[Copilot]

Pull request overview

This PR aims to reduce the bundle size of the browser-targeted encoding entrypoint (@exodus/bytes/encoding-browser.js) by relying more on native browser TextDecoder behavior and by consolidating encoding-label utilities into fewer modules.

Changes:

• Consolidates normalizeEncoding, labelToName, and E_ENCODING into fallback/encoding.js and strips them out of fallback/encoding.api.js.
• Reworks encoding-browser.browser.js to avoid importing the full labels dataset and instead normalize/validate via native TextDecoder.
• Updates vendor mocks and adds a new browser-focused test suite for encoding-browser.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
whatwg.js	Switches to importing encoding helpers from ./fallback/encoding.js (consolidated module).
tests/vendor/whatwg-encoding/whatwg-encoding-mock.js	Uses @exodus/bytes/encoding-browser.js instead of the full encoding.js entrypoint.
tests/encoding/browser.test.js	Adds browser-specific coverage for native TextDecoder/TextEncoder behavior and hooks.
fallback/encoding.js	Becomes the home for normalizeEncoding, labelToName, and E_ENCODING (previously in encoding.api.js).
fallback/encoding.api.js	Reduced to fromSource and getBOMEncoding only.
encoding-browser.browser.js	Implements lightweight browser normalization/hooks intended to reduce bundle size.

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