fix: skip unnecessary network reset during emulation restore

[dhananjay6561]

solves #1797

Summary

Fixes a Lighthouse audit failure where Network.emulateNetworkConditions could hang during emulation restore.

Root cause

lighthouse_audit always runs restoreEmulation() in a finally block.
During restore, McpContext.emulate() always called page.emulateNetworkConditions(null) when networkConditions was not set.
On some Chrome/CDP combinations, that reset call can time out even though no network emulation was active.

What changed

• Added an internal skipNetworkReset option to McpContext.emulate().
• Updated restoreEmulation() to skip the network reset when the page had no saved networkConditions.
• Kept all other emulation restore behavior unchanged.

Validation

• npm run test:no-build -- tests/McpContext.test.ts
• npm run test:no-build -- tests/tools/lighthouse.test.ts

Risk

Low. The change only avoids one unnecessary network-reset call when there was nothing to reset.

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[dhananjay6561]

@Lightning00Blade hi!
kindly review the pr!