feat(standup): standup automatique hier/aujourd'hui/blocages (issue #6)

format_standup_text + _standup_data (journal de la veille, focus
du jour, vieillissantes QA/Révision); page /standup copiable,
/api/standup; inclusion optionnelle au briefing ntfy
(KANBANTE_BRIEFING_INCLUDE_STANDUP).

app/templates/digest.html

@@ -17,6 +17,7 @@
             <a href="/my" class="nav-pill">👤 Mes issues</a>
             <a href="/activity" class="nav-pill">📰 Activité</a>
             <a href="/briefing" class="nav-pill">📊 Briefing</a>
+            <a href="/standup" class="nav-pill">🗣️ Standup</a>
             <a href="/search" class="nav-pill">🔍 Recherche</a>
             <a href="/capture" class="nav-pill">⚡ Capture</a>
             <a href="/digest" class="nav-pill active">🧠 Digest</a>