U7: Update docs, public copy, and verification

[breadback00-dev]

Parent: #16

Purpose

Make the horror pass testable, explainable, and safe to hand to playtesters.

Scope

• Update public copy to describe the psychological-horror layer without exposing private lore or overselling intensity.
• Add a horror-specific browser playtest path covering opening, first instability, consent choice, action trace, debrief, mute/reduce-intensity, and reset.
• Keep the first-8-minute playtest focused on onboarding/discovery with a short note that a later horror pass exists.
• Add/update scripts so syntax checks and pure helper tests run cleanly.

Target files

• Case Box 001 - The Creator Who Left But Kept Posting/README.md
• Case Box 001 - The Creator Who Left But Kept Posting/docs/game-design.md
• Case Box 001 - The Creator Who Left But Kept Posting/docs/case-authoring.md
• Case Box 001 - The Creator Who Left But Kept Posting/docs/first-8-minute-playtest.md
• Case Box 001 - The Creator Who Left But Kept Posting/docs/psychological-horror-playtest.md
• Case Box 001 - The Creator Who Left But Kept Posting/package.json

Acceptance checks

• README still gives one obvious way to run the prototype.
• Public docs describe simulated privacy/identity pressure without requiring private source docs.
• npm run check passes.
• npm test passes once tests are added.
• Browser playtest confirms canonical/divergent reconstructions, invasive/protective consent paths, mute/reduced-intensity controls, reset, and mobile layout.