Task 16 — daily digest (news-server/src/notify/digest.rs)
==========================================================

What was built
--------------
- NEW crates/news-server/src/notify/digest.rs
  - pub async fn build_and_send_digest(pool, scorer, ntfy, config, now)
  - Due-time gate: today's 07:00 in now.timezone(); before that -> Ok(()) debug log.
  - Idempotency gate: SELECT COUNT(*) FROM notification_log WHERE lane = 'digest' AND created_at >= ?1 (today's 07:00 UTC RFC3339).
  - Queries story_clusters created in the last 24h joined to canonical raw_items.
  - Scores canonical items, skips blocklisted (NEG_INFINITY) and opinion pieces when notify_opinions = false.
  - Band check: score in [p75, p90) of the trailing-7-day relevance distribution via PercentileTracker.
  - Sends one ntfy request via NtfyPublisher::publish_digest with Title, Priority: 2, Markdown: yes, Tags: newspaper, bullet-list body.
  - Records one notification_log row with Uuid::nil(), lane='digest', source_count_at_notify=<story count>, dry_run=0.
  - No token-bucket interaction.
- MODIFIED crates/news-server/src/notify/ntfy.rs
  - Added NotifyError::{Store, Sql, Server} #[from] variants.
  - Added pub async fn publish_digest(title, body_markdown).
  - Factored retry-once logic into private send_with_retry(Fn() -> RequestBuilder) so publish() behavior/tests are unchanged.
- MODIFIED crates/news-server/src/notify/mod.rs
  - Added pub mod digest.

Test names added
----------------
notify::digest::tests::
  - skips_when_no_eligible_stories
  - sends_digest_with_in_band_stories
  - second_call_same_day_is_no_op
  - before_seven_am_is_no_op
  - excludes_opinion_when_notify_opinions_false
  - includes_opinion_when_notify_opinions_true

Opinion flagging representation
-------------------------------
- news-core/src/model.rs: RawItem.kind is ItemKind::{News, Opinion}.
- news-store/migrations/0001_init.sql: raw_items.kind TEXT NOT NULL stores "news" or "opinion".
- The digest filters on the joined canonical raw_items.kind column; no new migration or column was needed.

Verification
============

$ cargo test -p news-server
...
running 26 tests
...
test notify::digest::tests::skips_when_no_eligible_stories ... ok
test notify::digest::tests::excludes_opinion_when_notify_opinions_false ... ok
test notify::digest::tests::includes_opinion_when_notify_opinions_true ... ok
test notify::digest::tests::sends_digest_with_in_band_stories ... ok
test notify::digest::tests::before_seven_am_is_no_op ... ok
test notify::digest::tests::second_call_same_day_is_no_op ... ok
...
test result: ok. 26 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

$ cargo fmt --all --check
(no output, exit 0)

$ cargo clippy --workspace --all-targets -- -D warnings
    Checking news-server v0.1.0 (/home/connor/docs/projects/news/crates/news-server)
    Finished dev profile [unoptimized + debuginfo] target(s) in 5.29s

Captured happy-test ntfy request body
-------------------------------------
(temporarily instrumented sends_digest_with_in_band_stories to eprintln the wiremock request body, then removed the instrumentation)

CAPTURED_DIGEST_BODY:
- [Story 2](https://example.test/2)
- [Story 1](https://example.test/1)
- [Story 0](https://example.test/0)

The single POST to /news-triage carried:
  Title: Daily digest: 3 stories
  Priority: 2
  Markdown: yes
  Tags: newspaper
  body as shown above.