fix: QOTD/WOTD freshness — pick within the freshest cohort, not the rotated pool

Both selectors ordered candidates least-recently-shown, then daily.seeded_order()
ROTATED the whole list and took [0] — an arbitrary date-hashed item, undoing the
ordering. Result: repeats (quote id 2 on 6/28+6/29; word "harmony" on 6/25+6/28),
no guarantee a pool item is shown before it recurs.

Fix: daily.freshest(rows) returns the freshest cohort only — every NEVER-shown
item while any remain, else the oldest-shown group. quote/wotd _candidates use it;
seeded_order now picks deterministically WITHIN that cohort. So every pool item is
featured once before any repeat, then cycles oldest-first. Dropped the unused
_NO_REPEAT_POOL window. Tests: no-repeat-until-exhausted (quote + wotd) + a
freshest() unit test. 428 backend tests green.

(Separate follow-up: expand the QOTD pool from 16 → 90+ vetted public-domain
quotes for a longer no-repeat window.)

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

goodnews/wotd.py

@@ -25,7 +25,6 @@ from .localtime import local_today
 
 DICT_BASE = "https://api.dictionaryapi.dev/api/v2/entries/en"
 _UA = {"User-Agent": "upbeatBytes/1.0 (+https://upbeatbytes.com)"}
-_NO_REPEAT_POOL = 60
 _TARGET_POOL = 30          # keep harvesting (a batch/day) until the pool reaches this
 _HARVEST_BATCH = 12
 _MIN_AUDIO_BYTES = 500
@@ -222,11 +221,10 @@ def _candidates(conn: sqlite3.Connection, avoid: int | None = None) -> list[int]
     if featured:
         ids = [r[0] for r in featured]
     else:
-        rows = conn.execute(
-            "SELECT id FROM wotd_pool WHERE blocked=0 ORDER BY shown_at IS NOT NULL, shown_at, id LIMIT ?",
-            (_NO_REPEAT_POOL,),
-        ).fetchall()
-        ids = [r[0] for r in rows]
+        # The freshest cohort only (never-shown, else the oldest-shown group) — picking
+        # across the whole pool is what re-fed recent words day to day.
+        rows = conn.execute("SELECT id, shown_at FROM wotd_pool WHERE blocked=0").fetchall()
+        ids = daily.freshest(rows)
     if avoid is not None:
         ids = [i for i in ids if i != avoid] or ids
     return ids