feat: add AI-powered release announcement system

[lane711]

Summary

Adds automated release announcements to Discord, Twitter/X, and WWW website when a new release is published.

• Post to Discord with rich embed (highlights, install command, links)
• Post to Twitter/X with concise announcement + hashtags
• Create PR on WWW repo to update changelog and version badge

How it works

1. Claude Code generates content - No API costs, you ask Claude Code to generate the release writeup
2. Content saved to .release-content.json - Claude writes the JSON file
3. Run npm run release:announce - Script reads content and posts to all platforms

New files

scripts/release/
├── index.js           # Main orchestrator
├── generate-content.js # Reads pre-generated content
├── post-twitter.js    # Twitter API v2 integration
└── update-www.js      # GitHub API for WWW repo PRs

.github/workflows/
└── release-announce.yml  # Triggered on release publish

New npm scripts

Command	Description
npm run release:announce	Post to Discord, Twitter, create WWW PR
npm run release:announce:dry	Test without posting

Required secrets

Secret	Purpose
DISCORD_WEBHOOK_URL	Discord posting
TWITTER_API_KEY	Twitter API
TWITTER_API_SECRET	Twitter API
TWITTER_ACCESS_TOKEN	Twitter API
TWITTER_ACCESS_SECRET	Twitter API
WWW_REPO_TOKEN	GitHub PAT for WWW repo PRs

Test plan

• Dry run works locally
• Test workflow via manual trigger with dry run
• Test actual posting to Discord
• Test actual posting to Twitter

Closes #358

🤖 Generated with Claude Code