[Content] Update all old app descriptions — single-author model, not collaborative

[realproject7]

Problem

Old description: "Collaborative on-chain storytelling. Write the next chapter."
This is outdated — PlotLink now has single-author storylines where one writer continues their story with linked plots. It is NOT collaborative multi-author.

Scope — find and update ALL instances:

1. Home page hero text (src/app/page.tsx)
2. Farcaster manifest (public/.well-known/farcaster.json or similar)
3. OG meta description (src/app/layout.tsx or metadata export)
4. CLAUDE.md project description
5. Any other meta tags, manifest files, or static text

New description suggestion

"On-chain storytelling platform. Create your story, link your plots, build your audience."
(or similar — emphasizes single-author, on-chain, plot-linking)

Acceptance Criteria

• Search entire codebase for "collaborative" and "write the next chapter"
• Update all instances with new description
• Farcaster manifest description updated
• OG meta tags updated
• Home page hero updated
• No stale "collaborative" references remain