docs: news sources research: one publisher, Google News, greencloud test

- Why not a browser per user: a full engine per install and fetch, each
  user facing the challenge, IDX seeing thousands of scrapers; one
  scheduled publisher serving static files instead (diagram). Hosting
  left open (GitHub release, Cloudflare Pages/R2, a Worker).
- The IDX challenge is JavaScript-based: curl fails from a second
  datacenter (greencloud-vps, Singapore) too, so IP is not what curl
  lacks.
- Other sources measured: Google News RSS covers companies MSN misses
  (BREN 75/100 titles naming the ticker in 7 days), plain HTTP; Yahoo
  search answers 429.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V3syn2fN2LNo5pvTSqc6eh

AGENTS.md

@@ -33,7 +33,7 @@ Docs:
 - `docs/OWNERSHIP_SYNC.md` / `docs/OWNERSHIP_PUBLISH.md`: snapshot consumer contract / maintainer publishing
 - `docs/SMOKE.md`: Nix checks, test layout, and the live drift check
 - `docs/DESIGN.md`: idx-core / idx-mcp design and parity gates
-- `docs/IDX_NEWS.md`: IDX news and disclosures research, proposed publisher design
+- `docs/IDX_NEWS.md`: news sources research (IDX disclosures, Google News, Yahoo) and a proposed publisher design
 - `ROADMAP.md`: open work
 
 ## Rules