feat: add stickiness round — daily Sadaqah tracker + Family Tree social loop

Two features scoped from the stickiness brainstorm, sharing one digest
notification pipeline:

Sadaqah tracker (new tab): a private daily giving journal, not a payment
processor — the app logs, it never moves money. Streak tracking follows
the proven pattern from dedicated apps (Sidq, Daily Sadaqa). Family
visibility is strictly limited to streak counts via a SECURITY DEFINER
RPC (nf_family_sadaqah_streaks) — amounts, causes, and notes never cross
the member boundary, respecting the Islamic preference for giving
privately. Entries can be dedicated 'in memory of' a deceased person from
the Family Tree, with a memorial count (nf_memorial_sadaqah_count, count
only) surfacing on that person's card.

Family Tree social loop: a 'give sadaqah in memory of' link on every
deceased person's card (cross-tab jump via a small requestedTab store in
nav.js), plus completeness hints (missing birth date, missing photo,
no relationships linked) feeding directly into the existing Coverage
Dashboard recommendations engine rather than a new UI surface.

Daily digest Edge Function + pg_cron (07:00 UTC): batches into one email
per family member per day, sent only when there's real content — tree
activity in the last 24h, a birthday/death-anniversary today, or a
weekly sadaqah recap on Sundays. An empty day sends nothing, deliberately
avoiding the notification-spam failure mode the research flagged.
Protected by a shared secret header since it's cron-invoked, not
user-triggered. Verified with a live manual invocation before relying on
the schedule.

Found and fixed two real bugs in nf_family_sadaqah_streaks during E2E
testing: an ambiguous unqualified 'member_id' column reference colliding
with the function's OUT parameter (42702), and a bigint/int type mismatch
from count(*) (42804) — both would have 400'd on every call in production.

Covered by e2e-sadaqah-tree.cjs (12/12). Full regression: 280/280 across
all suites.

src/lib/FamilyTree.svelte

@@ -9,8 +9,9 @@
   import {
     listPeople, addPerson, updatePerson, removePerson,
     uploadPersonPhoto, removePersonPhoto, getPersonPhotoUrl,
-    listRelationships, addRelationship, removeRelationship
+    listRelationships, addRelationship, removeRelationship, getMemorialSadaqahCount
   } from './db.js';
+  import { requestedTab } from './nav.js';
   import InfoPanel from './InfoPanel.svelte';
   import Disclaimer from './Disclaimer.svelte';
 
@@ -20,6 +21,7 @@
   let people = $state([]);
   let relationships = $state([]);
   let photoUrls = $state({}); // personId -> signed url
+  let memorialCounts = $state({}); // personId -> count
   let error = $state('');
 
   let form = $state({ fullName: '', gender: '', birthDate: '', deathDate: '', notes: '' });
@@ -39,6 +41,14 @@
       people.filter(p => p.photoPath).map(async p => [p.id, await getPersonPhotoUrl(p.photoPath)])
     );
     photoUrls = Object.fromEntries(entries);
+    const memorialEntries = await Promise.all(
+      people.filter(p => p.deathDate).map(async p => [p.id, await getMemorialSadaqahCount(p.id)])
+    );
+    memorialCounts = Object.fromEntries(memorialEntries);
+  }
+
+  function giveInMemory() {
+    requestedTab.set('Sadaqah');
   }
 
   onMount(refresh);
@@ -239,6 +249,14 @@
         {#if expandedId === p.id}
           <div class="person-detail">
             {#if p.notes}<p class="notes">{p.notes}</p>{/if}
+            {#if p.deathDate}
+              <div class="memorial-row">
+                {#if memorialCounts[p.id] > 0}
+                  <span class="memorial-count">{memorialCounts[p.id]} sadaqah given in their memory</span>
+                {/if}
+                <button class="btn-small" onclick={giveInMemory}>Give sadaqah in memory of {p.fullName}</button>
+              </div>
+            {/if}
             <div class="photo-controls">
               <label class="upload-btn">
                 {uploadingFor === p.id ? 'Uploading…' : (photoUrls[p.id] ? 'Replace photo' : 'Upload photo')}
@@ -328,6 +346,8 @@
   .muted { color: #8A8478; font-size: 11px; }
   .person-detail { padding: 0 12px 12px; }
   .notes { font-size: 12px; color: #B8B2A6; margin-bottom: 10px; }
+  .memorial-row { display: flex; flex-direction: column; gap: 6px; margin-bottom: 10px; }
+  .memorial-count { font-size: 11px; color: #C9A84C; }
   .photo-controls { display: flex; gap: 8px; margin-bottom: 10px; align-items: center; }
   .upload-btn { position: relative; background: rgba(201,168,76,0.15); color: #C9A84C; border-radius: 8px; padding: 8px 12px; font-size: 12px; cursor: pointer; font-weight: 600; }
   .upload-btn input[type=file] { position: absolute; inset: 0; opacity: 0; cursor: pointer; }