docs(talk-like-scarletkc): refine technical threads and sourcing

[scarletkc]

Technical explainers were coming out as dense documentation, and drafts kept repeating research-status caveats after the author supplied a confirmed observation. This updates Social mode to choose information for the reader and keep sourcing discussions outside publishable copy.

Changes:

• Lead with a concrete reader impact; move supporting technical detail into replies when it improves readability, without requiring every post to be a thread.
• Preserve author-confirmed observations within their stated scope, distinguish them from official confirmation, and keep actual limitations.
• Keep “not found” and “still checking” research narration outside the draft; omit or narrow unsupported claims instead of converting unknowns into negative claims.
• Respect the author's latest edited or published version.
• Add three fictional evaluation cases. No actual published posts or screenshots are added, and the other writing modes are unchanged.

Validation:

• Ran the skill-creator quick validator: Skill is valid!
• Parsed evaluation JSON, checked unique IDs and case structure, and verified all 34 existing cases are unchanged.
• Reviewed the focused diff. The three new behavioral cases are specified but have not been run against a separate model.
• Repository CI will run its existing test and packaging checks.

No code, schemas, public APIs, or compatibility surfaces change.