docs: rewrite TUTORIAL.md as a short first-run path

[makefunstuff]

Summary

Rewrite docs/TUTORIAL.md so a first run is readable in one sitting.

The old tutorial mixed a first-run walkthrough, a classifier essay, greenfield digressions, three measured rule case studies, and a floor-noise lab. That reads as LLM salad even when the facts are good.

Changes

• One linear path: install → decide key → attach → one rule → find → act → second save
• Exactly one rule example (unwrap-in-handlers)
• Measurements, workflow philosophy, and floor lab removed from the tutorial (still reachable via GUIDE / MODEL links)
• Follows docs/STYLE.md (no throat-clearing, no "not X but Y" framing in prose)

Out of scope

• GUIDE.md / README.md still need a pass — same slop problem, separate PR
• No code changes; PROTOCOL.md untouched

How to review

Read docs/TUTORIAL.md top to bottom once. You should know what to type next at every step without opening GUIDE first.