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>

frontend/src/routes/+page.svelte

@@ -303,6 +303,17 @@
     }
   }
 
+  // The finite-ending's gentle nudge: one tap to get tomorrow's brief by email.
+  let digestBusy = $state(false);
+  async function subscribeDigest() {
+    if (!auth.user) { showSignIn = true; return; }      // sign in, then enable below
+    if (auth.user.digest_enabled || digestBusy) return;
+    digestBusy = true;
+    try { await postJSON('/api/account/digest', { enabled: true }); await refreshAuth(); }
+    catch { /* leave as-is */ }
+    finally { digestBusy = false; }
+  }
+
   const MIX_EVENT = { notToday: 'not_today', lessLikeThis: 'less_like_this', alwaysHide: 'hide_topic' };
   function applyAction(kind, value) {
     applyPrefAction(kind, value); // updates + persists + syncs to account
@@ -430,7 +441,17 @@
               </div>
             {/if}
           </section>
-          <p class="endcap rise">✦ that's the good news for today ✦</p>
+          <div class="endcap rise">
+            <p class="endmark">✦ that's the good news for today ✦</p>
+            <p class="endsub">You're caught up — see you tomorrow.</p>
+            {#if auth.user?.digest_enabled}
+              <p class="digestnote">Tomorrow's brief is headed to your inbox ☕</p>
+            {:else}
+              <button class="digestcta" onclick={subscribeDigest} disabled={digestBusy}>
+                {digestBusy ? '…' : 'Get tomorrow’s brief by email'}
+              </button>
+            {/if}
+          </div>
         {:else}
           <p class="muted center pad">No highlights yet today — try a calmer filter, or check back soon.</p>
         {/if}
@@ -532,6 +553,15 @@
     text-align: center; color: var(--muted); font-family: var(--serif);
     font-style: italic; margin: 40px 0 10px; letter-spacing: 0.02em;
   }
+  .endcap .endmark { margin: 0; }
+  .endcap .endsub { margin: 4px 0 0; font-size: 0.92rem; }
+  .endcap .digestnote { margin: 14px 0 0; font-style: normal; font-family: var(--label); font-size: 0.86rem; color: var(--accent-deep); }
+  .endcap .digestcta {
+    margin-top: 16px; font-family: var(--label); font-style: normal; font-size: 0.9rem; cursor: pointer;
+    background: var(--accent); color: #fff; border: none; border-radius: 999px; padding: 10px 22px;
+  }
+  .endcap .digestcta:hover { background: var(--accent-deep); }
+  .endcap .digestcta:disabled { opacity: 0.6; cursor: default; }
   .loadmore { display: flex; justify-content: center; margin: 30px 0 6px; }
   .loadmore button {
     background: var(--surface); border: 1px solid var(--line); color: var(--accent-deep);