README is outdated — still references fhenixjs branding, wrong install commands, broken badges

[giwaov]

Summary

The cofhejs README appears to be carried over from the old fhenixjs package and hasn't been updated to reflect the current project.

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Issues

Problem	Current (Incorrect)	Should Be
npm badge	Points to fhenixjs	Should point to cofhejs
CI badge	Points to fhenixprotocol/fhenix.js repo	Should point to cofhejs
Install command	npm install fhenixjs	npm install cofhejs
CDN link	fhenixjs@0.3.0-alpha.1	Should reference cofhejs
Docs link	fhenixjs.fhenix.zone	Should point to cofhe-docs.fhenix.zone
Title	"The JavaScript SDK for Fhenix"	Should mention CoFHE
Description	"fhenix.js allows developers..."	Should reference cofhejs

Additional Notes

• The line "(only node 20+ is supported until I fix this)" reads as a personal dev note rather than documentation. The package.json already declares "engines": { "node": ">=20.0.0" }, so the README should just state the requirement cleanly.
• The NextJS WASM config section references a TODO tracking next.js/issues/25852 — worth checking if that's still relevant.
• The current npm version is 0.4.0-alpha.0 but nothing in the README reflects the current API surface (cofhejs.encrypt, Encryptable.*, permit system, etc.).

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Happy to submit a PR updating the README if that would be helpful.