Rip out Ollama: direct_route only, no LLM layer

Pete moves to a remote host without Ollama access. Every source must
declare a direct_route channel; the classifier, explainer, semantic
dedup, !explain summaries, feed_hint, and the recent_headlines /
classification_log tables are gone. Deterministic dedup (canonical URL,
headline_norm, per-channel cooldown) remains.

internal/scheduler/roundrobin_test.go

@@ -33,7 +33,6 @@ func insertPostable(t *testing.T, guid, source, channel string, seenAt int64) {
 		Lede:       "Lede for " + guid,
 		ArticleURL: "https://example.com/" + guid,
 		Source:     source,
-		FeedHint:   "tech",
 		SeenAt:     seenAt,
 	}); err != nil {
 		t.Fatalf("InsertStory(%s): %v", guid, err)