The agreement to lift the blockade was only partial,

Are you sure?

The agreement called on Israel to increase the level of goods entering Gaza by 30 percent over the pre-lull period within 72 hours and to open all border crossings and “allow the transfer of all goods that were banned and restricted to go into Gaza” within 13 days after the beginning of the ceasefire.

I found this on Wikipedia, so I think you might be misremembering. Israel tried to get away with doing 2/3 of the bare minimum, “just to get started” part. The full agreement obligated them to just lift the whole thing within 13 days.

Does it? Was Gaza peaceful before the airstrikes and the blockade? (No)

I mean before that Gaza was like the West Bank right now. It’s arguable whether that’s better or worse than what’s happening right now, but there was still a clear injustice to fight against. Israel wasn’t letting Gazans live before 2005.

The Palestinians feel, not incorrectly, that they’ve been reduced to second-class citizens under the occupation of another country. “They aren’t bombing us right now” is a minor offense in comparison.

“They aren’t bombing us right now” and “They aren’t blockading us” does fulfill the major demands Hamas has been making since 2005. The Great Injustice that Gaza-based Palestinian resistance is fighting against is the blockade and Israeli airstrikes. If you take away those the rest will work out one way or another. The blockade is to Gaza what settlements are to the West Bank; it basically is the occupation.

Can’t they? Peace would offer a great opportunity for an unrestricted Hamas to prepare for another war.

You can’t liberate people who aren’t occupied. That’s why they can’t do much if there’s peace.

Israel has offered ceasefire terms which would restrict their ability to prepare for another war,

Did they (as in: did they agree to lift the blockade in those terms)? I’m not aware of anything like that.