Phase 3: two-axis scoring and routing

Scoring (news/score.py): every profile block is embedded and compared by
z-score WITHIN block, then weighted. Veto fires on absolute similarity OR a
margin over the interest signal; demotes apply a penalty instead of excluding,
because those categories sit adjacent to real interests.

Importance is deliberately NOT corroboration count -- the old system's error,
which measured the subscription list rather than the news. It combines block
similarity, corroboration, burst velocity, editorial prominence and aggregator
score, all weighted from config.

Routing (news/route.py): two lanes with separate budgets. Interest never
overrides quiet hours; importance may, within a hard nightly cap. Vetoes are
absolute on BOTH lanes -- the v0.2 bypass lane never consulted relevance, so a
blocklisted item could still fire at priority 5, and a test now asserts it
cannot. Budgets are spent strongest-first rather than first-come.

Measured on 1,318 real clusters: 2.5 notifications/day and a 14-item digest,
inside the 2-5/day target.

Three defects the real data exposed, none of which unit tests would have caught:

- velocity was computed as origins/hours with a 0.5h floor, giving every
  SINGLE-source cluster a spurious velocity of 2.0. Growth rate is undefined
  for a cluster that has not grown; it is now zero below two origins.
- deferred items (quiet hours, budget exhausted, immature) settled straight
  into the digest and bypassed its cap, producing 198 items/day. Everything
  that misses an alert lane now competes for one ranked, capped digest.
- feeds return large archives on first fetch -- 88 Strong Towns items going back
  five months, and a BBC entry titled "BBC News app" dated 2025. Those belong in
  the scoring population but must never notify, so routing now has a recency
  requirement.

Reading the output also found two profile gaps: recurring columns and link
round-ups ("Catching Our Eye News Roundup", "Astronomy Picture of the Day")
scored as top-ranked interest items. They are on-topic but publish on a
schedule, so they are demoted rather than vetoed and still reach the digest.

profile/profile.toml

@@ -338,6 +338,21 @@ probes = [
   "A missing person case takes a turn as investigators search a rural property.",
 ]
 
+# Recurring columns, link round-ups and daily photo features. These are often
+# genuinely on-topic -- Astronomy Picture of the Day matches space-aerospace
+# correctly -- but a feature that publishes on a schedule is not news breaking,
+# and should never be an interruption. Demoted rather than vetoed so they still
+# reach the digest.
+[[demote]]
+id = "recurring-feature"
+penalty = 1.5
+probes = [
+  "Catching Our Eye: a round-up of links and short items we noticed this week.",
+  "Astronomy Picture of the Day: today's image, with a short explanatory caption.",
+  "Your morning briefing: everything you need to know today, in five bullet points.",
+  "This week in review: the stories we covered, collected.",
+]
+
 # ============================================= the importance lane ===========
 # Independent of interest. Vetoes still apply here -- v0.2's bypass lane ignored
 # relevance entirely (gate.rs:302), which let blocklisted items fire at priority 5.