KOL feeds: fix dead/blocked sources, drop stale feeds (29→25)

Feed-health pass over KOL_FEEDS:
- raoulpal: stale Substack (last 2024-05) → Real Vision podcast feed
- dampedspring: paywalled (0 entries) → free "Damped Spring 101" Substack
- unchained: Cloudflare 403 → canonical Megaphone podcast feed
- lynalden: Cloudflare 202 → FeedBurner mirror
- glassnode: recovered via httpx http2=True (was 403 on HTTP/1.1)
- browser User-Agent + Accept headers on feed fetch
- removed dead feeds with no active replacement: placeholder,
  dragonfly, niccarter, eugene
- pin h2==4.3.0 (required by http2=True)

All 25 remaining feeds verified fetching real body content; newest
post per feed ≤88d. Bundles in-flight KOL-module work already in the
working tree (kol_x ingest, migration 027, tests).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/config.py

@@ -90,6 +90,15 @@ class Settings(BaseSettings):
     # Public site URL appended to the follow-up tweet. Falls back to frontend_url.
     x_link_url: str = ""
 
+    # ── X (Twitter) READ — KOL tweet ingestion (separate from the poster above) ──
+    # twitterapi.io managed-scraper key, sent as the `x-api-key` header. Powers
+    # kol_x.py: polls each tracked KOL's recent tweets → x_analysis.analyze_x_post
+    # → KolPost(source="twitter") → kol_divergence. This is READ-ONLY third-party
+    # data and is UNRELATED to the OAuth 1.0a poster creds above (those write our
+    # own tweets; this reads other people's). Empty = X ingestion disabled (no-op).
+    # Get a pay-as-you-go key at twitterapi.io (~$0.15 / 1k tweets).
+    twitterapi_io_key: str = ""
+
     model_config = {"env_file": ".env", "env_file_encoding": "utf-8", "extra": "ignore"}