- Wire onPartialReply in dispatchReplyWithBufferedBlockDispatcher to enable
  preview streaming: tokens now arrive progressively instead of all at once
- Pre-create placeholder message before dispatch (onPartialReply is fire-and-forget)
- Replace all hand-rolled loadEnv() functions with dotenv library
- Add .env.example with placeholder values (safe to commit)
- Add setup-app.ts for provisioning a new Stream Chat app
- Fix test-client.ts streaming display: track lastSeenText per message to
  print only delta characters instead of repeating cumulative text
- Print message IDs in test-client.ts for easier thread/quote testing
- Update CLAUDE.md with accurate inbound flow and key design decisions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

- All scripts now load dotenv from their own directory via
  config({ path: new URL(".env", import.meta.url).pathname })
- setup-app.ts writes scripts/.env instead of project root .env
- Remove BOT_USER_ID from .env.example (not needed by scripts at runtime)
- Update .gitignore to match new paths

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>