docs: ai-assets.md is thin, omits the AI-tagged entries and has no dated Steam disclosure quote #180

Why it matters

The catalog now contains AI content (#163 Soundza, BudgetPixel, the two BitNuker samplers, 3DTexel's mixed SKUs), and Steam requires AI disclosure. The guide a developer would read before shipping still holds research notes rather than guidance.

Evidence

• docs/ai-assets.md is 28 lines long.
• Its "Related entries" list omits budgetpixel-sfx, bitnuker-workshop-sampler, bitnuker-fantasy-environments-sampler, soundza and 3dtexel.
• The Steam section says only to check current Valve guidelines, with no dated quote.

Suggested approach

• List the tagged entries, or link a live ?q=ai-generated view so the list never drifts.
• Quote Valve's current content-survey AI disclosure rule with the date it was read.
• Spell out what using an ai-generated entry obliges a developer to disclose.
• Add a validator check that entries whose body says content is AI-generated carry the tag.

Done when

The guide lists or links every AI-tagged entry, includes a dated Steam quote, and the validator keeps tagging consistent.