docs(changelog): finalize v3.4.0 release notes

[rjan90]

Summary

• finalize the v3.4.0 changelog date after Calibration and Mainnet execution
• record the active PDPVerifier implementation/proxy addresses
• add proxy upgrade transaction links for both networks
• record the exact deploy commit used for the implementation contracts
• update release wording now that both proxies report VERSION() == "3.4.0"

Deployment

• Deploy commit: 1370f49f9af958e4e3a1396377035685d55ffdba
• Calibration implementation: 0xd60b90f6D3C42B26a246E141ec701a20Dde2fA61
• Calibration upgrade tx: 0x0bb3597820f0c14a902f6c5672e5b3d1e2f9b7e60174773af07ef6f2762121ad
• Mainnet implementation: 0xb41A97FEDD2D9497C639A643ec75E56CbCeDe8BA
• Mainnet upgrade tx: 0x07407b3becb1786e3b4217bfb5774d155d91d9688b0800fe5740689a72c4ed10

Validation

• Calibration proxy verified on VERSION() == "3.4.0", implementation slot, getChallengeFinality() == 10, and read-only smoke tests
• Mainnet proxy verified on VERSION() == "3.4.0", implementation slot, getChallengeFinality() == 150, and read-only smoke tests