[P2] util.js: relocate browser + clipboard helpers

**Parent Epic:** [#44552 — `util.js` decomposition](https://github.com/MetaMask/metamask-extension/issues/44552)
**Source:** `ui/helpers/utils/util.js`
**Size:** S

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## Problem

`getIsBrowserDeprecated` and `clearClipboard`. `getIsBrowserDeprecated` depends on the UI constant `OUTDATED_BROWSER_VERSIONS`, so a shared-side home would create a ui→constant back-reference.

## Solution

Place both in a small UI module `ui/helpers/utils/browser.ts` (alongside `is-mobile-view.js`) to keep the constant coupling UI-side; or `shared/lib/browser-runtime.utils.ts` if the constant is moved too. Rewire the 1–2 import sites.

## Acceptance Criteria

- [ ] Both helpers relocated; originals deleted; imports rewired; no ui→shared back-reference introduced. Tests green.

Start with ui/helpers/utils/util.js and trace the 1–2 import sites for getIsBrowserDeprecated and clearClipboard, then review the UI constant OUTDATED_BROWSER_VERSIONS and nearby ui/helpers/utils modules. Relocate both helpers to the agreed browser module, remove the originals, rewire imports without a ui→shared back-reference, and run the relevant tests until they are green.

Written by the indexing model from the issue text.