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>

alembic/versions/027_kol_post_analysis_fields.py

@@ -0,0 +1,30 @@
+"""Add tier / post_type / talks_vs_trades_flag / sentiment to kol_posts
+
+Revision ID: 027
+Revises: 026
+Create Date: 2026-06-05
+"""
+from alembic import op
+import sqlalchemy as sa
+
+revision = '027'
+down_revision = '026'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    with op.batch_alter_table('kol_posts') as batch:
+        batch.add_column(sa.Column('tier', sa.String(16), nullable=True))
+        batch.add_column(sa.Column('post_type', sa.String(16), nullable=True))
+        batch.add_column(sa.Column('talks_vs_trades_flag', sa.Boolean,
+                                   nullable=True, server_default='0'))
+        batch.add_column(sa.Column('sentiment', sa.String(16), nullable=True))
+
+
+def downgrade() -> None:
+    with op.batch_alter_table('kol_posts') as batch:
+        batch.drop_column('sentiment')
+        batch.drop_column('talks_vs_trades_flag')
+        batch.drop_column('post_type')
+        batch.drop_column('tier')