chore: remove date-fns dependency

[Uzlopak]

removes 7 MB of dependencies

[Copilot]

Pull Request Overview

This PR removes the date-fns dependency from the webrtc and dtls packages to reduce the bundle size by 7 MB. The dependency was only used for adding years to dates in certificate generation.

• Removes date-fns from package.json dependencies in both webrtc and dtls packages
• Replaces addYears function call with native JavaScript date manipulation

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
packages/webrtc/package.json	Removes date-fns dependency from webrtc package
packages/dtls/package.json	Removes date-fns dependency from dtls package
packages/dtls/src/context/cipher.ts	Replaces date-fns addYears function with native Date operations

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[Copilot]

Creating multiple Date objects is inefficient. Consider creating a single Date object and reusing it: const now = new Date(); notAfter: new Date(now.setFullYear(now.getFullYear() + 10))

Suggested change

	notAfter: new Date(new Date().setFullYear(new Date().getFullYear() + 10)),
	notAfter: (() => { const now = new Date(); const after = new Date(now); after.setFullYear(now.getFullYear() + 10); return after; })(),