Daily digest (opt-in) + finite "you're caught up" ending

Reader-retention as ritual, not capture (Codex's framing). Opt-in calm morning
email of today's brief; the on-site twin is the finite end-of-feed nudge.

* Schema: users.digest_enabled + digest_unsub_token; digest_sends (dedupe +
  visibility). auth.get_user now returns the digest fields.
* goodnews/digest.py: build (dated calm subject, items w/ summary + "why it's
  here" + UB/source links + one-click unsubscribe, "you're caught up" sign-off)
  and send_due_digests (morning-window gated, >=4-item floor or skip quietly,
  deduped, reuses SMTP). No streaks/urgency/"you missed".
* API: /auth/me exposes digest_enabled; POST /api/account/digest toggle;
  GET /api/digest/unsubscribe (token, no login, calm confirmation page).
* CLI: cycle gains a morning-gated digest step (--no-digest) + a send-digests
  command (--force).
* Frontend: digest toggle on the Account profile; the Highlights end-cap now
  says "you're caught up — see you tomorrow" with a one-tap "Get tomorrow's
  brief by email" (signed-in → enable; anon → sign in).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

goodnews/db.py

@@ -141,6 +141,8 @@ CREATE TABLE IF NOT EXISTS users (
     display_name TEXT,
     avatar_url TEXT,
     is_admin INTEGER NOT NULL DEFAULT 0,
+    digest_enabled INTEGER NOT NULL DEFAULT 0,
+    digest_unsub_token TEXT,
     created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
     updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
@@ -254,6 +256,15 @@ CREATE TABLE IF NOT EXISTS feedback_replies (
     sent_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
 CREATE INDEX IF NOT EXISTS idx_feedback_replies_fid ON feedback_replies(feedback_id);
+
+CREATE TABLE IF NOT EXISTS digest_sends (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    brief_date TEXT NOT NULL,
+    item_count INTEGER NOT NULL DEFAULT 0,
+    sent_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE (user_id, brief_date)
+);
 """
 
 
@@ -296,6 +307,10 @@ def _migrate(conn: sqlite3.Connection) -> None:
         conn.execute("ALTER TABLE users ADD COLUMN avatar_url TEXT")
     if user_tbl and "is_admin" not in user_tbl:
         conn.execute("ALTER TABLE users ADD COLUMN is_admin INTEGER NOT NULL DEFAULT 0")
+    if user_tbl and "digest_enabled" not in user_tbl:
+        conn.execute("ALTER TABLE users ADD COLUMN digest_enabled INTEGER NOT NULL DEFAULT 0")
+    if user_tbl and "digest_unsub_token" not in user_tbl:
+        conn.execute("ALTER TABLE users ADD COLUMN digest_unsub_token TEXT")
 
     article_cols = {row["name"] for row in conn.execute("PRAGMA table_info(articles)")}
     if "duplicate_of" not in article_cols: