[SaladDay]

Summary

This retires PARSAR_NODE_ENROLLMENT_TOKEN in every mode. Web's Add node command has passed the token on standard input (--enrollment-token-stdin) since #148, and the Core installer stopped using the variable in #152.

• Refusal: if the variable is set, the node installer refuses right after argument parsing, before any step runs, and in root, non-root and uninstall modes alike. It prints one line naming --enrollment-token-stdin and exits 2. There is no fallback.
• Unchanged paths: the stdin path and the hidden prompt work as before. A registered node can still rerun with its saved credential.
• New message: running a new node without a token now says to copy the command from Add node.
• Docs: line-local changes. The node guide wording is updated, and the operations upgrade table has a retirement row.

Verification

• The installer suite passes normally, under umask 077 and under nohup. The manifest tests also pass.
• The full local server gate passed on 0c0341a2, the exact head, which includes main ffb4ad59. The Playwright browser cases were skipped on the server, as approved (Chrome unavailable).
• Review: self-review. This is a small retirement following the repo's retired-name rule.

---

^{Need help on this PR? Tag @codesmith with what you need. Autofix is disabled.}