Rewrite docs/npm-releases.md for the release process in stack

[auxesis]

docs/npm-releases.md came over from cipherstash-suite in the import, #1001. It describes the suite's release process, and most of it is wrong in stack. freshtonic found this in review of #1001.

What is wrong

• It names release-npm.yml, publish-auth-npm.yml and publish-profile-npm.yml. None of these exists in stack.
• It names packages/stack-auth/node and packages/stack-profile/node. The bindings now live under languages/typescript/packages/.
• It says changesets never sees the platform packages. In stack, pnpm-workspace.yaml includes them.
• It says @cipherstash/profile publishes on the first Version Packages merge. build: import the stack-* crates, node bindings and Go module #1001 marks it private.

An agent that reads this file gets wrong instructions.

Fix

Rewrite it to describe how @cipherstash/auth releases from stack through release.yml, which #1009 sets up. Or add a note at the top saying it records the suite's old process, and move it into docs/plans/.