Add OmniSocials plugin

[Lighthart99]

📕 Read CONTRIBUTING.md first — it's the rulebook (every
field, the quality bar, the Awesome Score). Reviewers cite it by rule number (G1–G8, UC-n, PL-n).

What this adds

Checklist

• This PR adds exactly ONE new file under content/ (plus assets for this entry, if any).
• It follows CONTRIBUTING.md — required fields + the golden rules (G1–G8).
• npm run validate passes locally (schema, slug, vocabularies).
• slug is kebab-case and exactly matches the filename.
• I ran / used this myself end to end — it works today.
• Every URL in the frontmatter resolves to real, relevant content.
• The prompt body is the real, complete prompt — not a summary or a teaser.
• The entry body is plain markdown — no raw HTML (<script>, <iframe>, <style>, <form>, inline event handlers). CI rejects it (§8.5).
• I did NOT set verified_at or status: live — a maintainer sets those during verification (§10.1).
• This is not an ad. A listing that exists to funnel traffic to your product gets closed. Sponsor slots will exist for that — this isn't one.
• If this is someone else's work: author is the original creator, the origin is linked (source_url for a plugin, source_tweets[] for a use case), and scouted_by is me.
• If the source is a YouTube video: primary_source is kind: youtube-video with a youtube.com/watch, youtu.be/ or youtube.com/shorts/ URL, plus the video's real title and channel — those two are required because they are what the page shows if the player never loads. timestamp is optional and is written mm:ss.
• I license this contribution under CC BY 4.0 (attribution: entry author + grokbot.dev).

Where it came from

[asimac2001]

Merged and live — thanks for the clean submission. Reviewer pass verified omnisocials.com, the docs, the auth-gated MCP endpoint, and @omnisocials/mcp-server on npm, then flipped it to live and pulled your icon. One reviewer trim: pricing_note was over the 120-char schema cap. Your listing: https://grokbot.dev/plugins/omnisocials/ — there's a built-in 'share on X' button. 🎉