No one can change the contents of a CID, it's based on a hash.
IPNS associates a static address to changing content CIDs, easier to remember, write down etc. I've never had much luck persisting a IPNS association over time.
You could post the CID to an ethereum contract, or pubsub or some other decentralized platform.
I can recommend Callude, https://callude.wip2p.com (cause I created it)
It's a self hosted, p2p calendar. You run a WebIndexP2P backend, and then you can use any hosted version of Callude, could be the link above, IPFS, electron whatever you like. The UI is also response and works great as a PWA.
It's pretty basic at the moment, but works great as a shared calendar alternative to Google and the likes.
Feel free to ask me any questions.
I like how this sub is so laser focused on self hosted apps that most the answers just completely glossed over the "ass wound" part and provide useful feedback.
You could open with I want a self hosted app for keeping track of my serial murders, and people would come back with some great options.
I've been wanting to build a system just like this for a while. I started just jotting down all the information in a wiki and then never found any benefit from building a more structured system that the simple wiki already provides.
Happy to discuss in further detail, maybe even talk about prototyping something basic if you have some good suggestions.
I'm a big proponent of self-hosted apps, but I am not a fan of docker/containers so it's definitely not just for the sake of running containers for me.
Using free online services is convenient, but if ALL you use is online services then someone else or some company controls you. I like to self host as much as I possibly can. If we don't, cloud computing will take over, and home/consumer computer hardware will eventually die off.
I recently created WipWiki to solve 3 of your 4 points, search could be easily added though if your interested in collaborating.
You can play around with the UI here: https://wiki.wip2p.com
https://cheese.wip2p.com
P2P photo sharing. It auto compresses larger photos so its mainly for sharing the best photos with friends/family rather than a backup.