Limit detailed view to lineal kin; rest as summary bullets

Per-recipient: only direct ancestors and direct descendants
within a configurable number of generations (default 3) get the
full row treatment (avatar, icon, timeline). Everyone else falls
through to a compact text-only bullet list at the bottom of the
same section.

- New tree preference NEWSLETTER_LINEAL_DEPTH (range 0–10,
  default 3) with a clearly-explained admin input.
- RelationshipPathFinder::linealKin() does two cheap recursive
  expansions (ancestors and descendants only — no spouse or
  sibling traversal) and returns the xref set. Memoised per
  recipient within a dispatch run.
- Avatar attachments are filtered per recipient to only the
  embeds actually referenced in their HTML, so summary-only rows
  no longer inflate per-email size with unused images.
- Recipients with no PREF_TREE_ACCOUNT_XREF (external admin
  addresses, users not linked to a record) see the entire
  newsletter in detail — no lineal anchor to filter against.
- German translations for the three new section kickers ("Other
  birthdays", etc.) and the admin input help text.

src/Services/NewsletterDispatchService.php

@@ -173,6 +173,15 @@ final class NewsletterDispatchService
                 // record the recipient is linked to in this tree.
                 foreach ($group as $recipient) {
                     $relationships = $this->relationshipMap($tree, $recipient, $featured);
+                    $detailed_set  = $this->detailedXrefs($tree, $recipient, $featured);
+
+                    // Trim the embedded image set to only the avatars
+                    // we'll actually reference (detailed rows). Summary
+                    // bullets render without pictures.
+                    $recipient_avatars = array_intersect_key(
+                        $avatars,
+                        $this->avatarKeysForXrefs(array_keys($detailed_set)),
+                    );
 
                     $html = view($module->name() . '::email', [
                         'tree'                  => $tree,
@@ -186,13 +195,14 @@ final class NewsletterDispatchService
                         'generated_at'          => $now,
                         'avatar_cids'           => $avatar_cids,
                         'relationships'         => $relationships,
+                        'detailed_xrefs'        => $detailed_set,
                         'account_url'           => $account_url,
                     ]);
 
                     $text = $this->htmlToText($html);
 
                     try {
-                        if ($this->mailer->sendWithEmbeds($from, $recipient, $from, $subject, $text, $html, $avatars)) {
+                        if ($this->mailer->sendWithEmbeds($from, $recipient, $from, $subject, $text, $html, $recipient_avatars)) {
                             $sent++;
                         } else {
                             $failures++;
@@ -269,6 +279,69 @@ final class NewsletterDispatchService
         return $individuals;
     }
 
+    /**
+     * Which featured xrefs deserve the full detailed row (avatar +
+     * timeline) for this recipient?
+     *
+     * If the recipient is unmapped to the tree (external address or a
+     * user with no PREF_TREE_ACCOUNT_XREF), every featured xref counts
+     * as "detailed" — they have no lineal context to filter against.
+     *
+     * Otherwise, only the recipient's direct ancestors and descendants
+     * within Configuration::linealDepth() generations qualify. For
+     * Family records (anniversaries), either spouse being lineal
+     * promotes the row.
+     *
+     * @param array<string,Individual> $featured
+     *
+     * @return array<string,true>  Set of featured xrefs to render in detail.
+     */
+    private function detailedXrefs(Tree $tree, UserInterface $recipient, array $featured): array
+    {
+        $self_xref = $tree->getUserPreference($recipient, UserInterface::PREF_TREE_ACCOUNT_XREF);
+
+        if ($self_xref === '') {
+            // Unmapped recipient — no lineal anchor, show everything.
+            return array_fill_keys(array_keys($featured), true);
+        }
+
+        $self = Registry::individualFactory()->make($self_xref, $tree);
+
+        if (!$self instanceof Individual) {
+            return array_fill_keys(array_keys($featured), true);
+        }
+
+        $depth      = Configuration::linealDepth($tree);
+        $lineal_set = $this->relationship_finder->linealKin($self, $depth);
+
+        $detailed = [];
+
+        foreach ($featured as $xref => $_individual) {
+            if (isset($lineal_set[$xref])) {
+                $detailed[$xref] = true;
+            }
+        }
+
+        return $detailed;
+    }
+
+    /**
+     * Translates a list of xrefs into the cid-name keys used by the
+     * avatar embed map ("avatar-<xref>" => true). Lets us
+     * array_intersect_key the embeds map cheaply.
+     *
+     * @param  array<int,string> $xrefs
+     * @return array<string,true>
+     */
+    private function avatarKeysForXrefs(array $xrefs): array
+    {
+        $keys = [];
+        foreach ($xrefs as $xref) {
+            $keys['avatar-' . $xref] = true;
+        }
+        return $keys;
+    }
+
     /**
      * Build a "xref => relationship label" map for one recipient.
      *