Social post TTS: NPR-style attribution and reading

[shellen]

Problem

When TTS reads a social post, it just reads the raw body text without context about who posted it or on what platform.

Desired behavior

Read social posts like NPR would attribute a tweet:

"Jason Shellen posted on Bluesky: 'In the past, this core was referred to as an efficiency core...' — linking to a Six Colors article about Apple renaming its CPU cores."

Pattern: Author → Platform → Content → Context (linked articles, quoted posts)

What needs to happen

• Add social-post-aware pre-processing before TTS
• Detect social platform from frontmatter/URL
• Format as spoken attribution: "{Author} posted on {Platform}: '{content}'"
• Include context for linked URLs and quoted posts
• May need a TTS system prompt adjustment or markdown pre-processing step

Context

TTS pipeline is in viewer/07-tts.js. Social detection is in viewer/18-social.js (detectSocialPlatform, parseSocialAuthor).