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/Module.php

@@ -122,6 +122,12 @@ class Module extends AbstractModule implements ModuleCustomInterface, ModuleConf
                 'Living kin who will celebrate this fortnight.'
                                                               => 'Lebende Verwandte, die in den nächsten zwei Wochen feiern.',
                 'Marriages still intact.'                     => 'Noch bestehende Ehen.',
+                'Other birthdays'                             => 'Weitere Geburtstage',
+                'Other anniversaries'                         => 'Weitere Hochzeitstage',
+                'Other historical events'                     => 'Weitere historische Ereignisse',
+                'Detailed view depth (generations)'           => 'Detailansicht-Tiefe (Generationen)',
+                'Recipients see profile pictures, icons and the timeline only for their own direct ancestors and descendants within this many generations. Everyone else appears as a compact text list at the bottom of each section. Set to 0 to render the whole newsletter as text. Recipients with no linked tree record always see the full detailed view.'
+                                                              => 'Empfänger sehen Profilbilder, Symbole und Zeitachse nur für ihre eigenen direkten Vorfahren und Nachkommen innerhalb dieser Generationenzahl. Alle anderen erscheinen als kompakte Textliste am Ende des jeweiligen Abschnitts. Auf 0 setzen, um den gesamten Newsletter als Text darzustellen. Empfänger ohne verknüpftes Baumprofil sehen stets die vollständige Detailansicht.',
                 '%s birthday'                                 => '%s Geburtstag',
                 '%s wedding anniversary'                      => '%s Hochzeitstag',
                 'Birthday'                                    => 'Geburtstag',
@@ -231,6 +237,9 @@ class Module extends AbstractModule implements ModuleCustomInterface, ModuleConf
             $histLook  = Validator::parsedBody($request)
                 ->isBetween(7, 60)
                 ->integer('historical-' . $id, Configuration::DEFAULT_HISTORICAL_LOOKAHEAD);
+            $lineal    = Validator::parsedBody($request)
+                ->isBetween(Configuration::MIN_LINEAL_DEPTH, Configuration::MAX_LINEAL_DEPTH)
+                ->integer('lineal-' . $id, Configuration::DEFAULT_LINEAL_DEPTH);
             $annivs    = Validator::parsedBody($request)->string('anniversaries-' . $id, '0') === '1';
             $extras    = Validator::parsedBody($request)->string('extras-' . $id, '');
             $subject   = Validator::parsedBody($request)->string('subject-' . $id, '');
@@ -239,6 +248,7 @@ class Module extends AbstractModule implements ModuleCustomInterface, ModuleConf
             $tree->setPreference(Configuration::PREF_FREQUENCY_DAYS, (string) $frequency);
             $tree->setPreference(Configuration::PREF_LOOKAHEAD_DAYS, (string) $lookahead);
             $tree->setPreference(Configuration::PREF_HISTORICAL_LOOKAHEAD, (string) $histLook);
+            $tree->setPreference(Configuration::PREF_LINEAL_DEPTH, (string) $lineal);
             $tree->setPreference(Configuration::PREF_INCLUDE_ANNIVERSARIES, $annivs ? '1' : '0');
             $tree->setPreference(Configuration::PREF_EXTRA_RECIPIENTS, $extras);