feat(frontend): panneau détail de carte, badges d'âge, limites WIP

- drawer de détail: corps markdown rendu (marked + DOMPurify
  vendorés), commentaires, formulaire de commentaire vers Gitea;
  clic distingué du drag par la distance du pointeur
- badges ⏳ N j au-delà du seuil d'âge (rouge au double)
- en-têtes de colonnes: n/limite, classe .over en rouge, toast
  d'avertissement au dépôt dans une colonne saturée
- page activity.html, liens Activité dans dashboard et board

app/templates/activity.html

@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<html lang="fr" data-theme="dark">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Activité — Kanbante</title>
+    <link rel="icon" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><text y='.9em' font-size='90'>📰</text></svg>">
+    <link rel="stylesheet" href="/static/css/style.css">
+</head>
+<body>
+    <header>
+        <h1><a href="/">📋 <span class="gradient-text">Kanbante</span></a> <span class="sep">/</span> 📰 Activité</h1>
+        <nav>
+            <a href="/focus" class="btn-sm">🎯 Focus</a>
+        </nav>
+    </header>
+
+    <main class="focus-main">
+        <p class="focus-intro">Les {{ events|length }} derniers événements du journal — déplacements, créations, fermetures et commentaires, tous projets confondus.</p>
+        {% if not events %}
+        <p class="focus-empty">Aucun événement pour le moment. Le journal se remplit dès que des cartes bougent.</p>
+        {% endif %}
+        <div class="activity-list">
+            {% for e in events %}
+            <div class="activity-item">
+                <span class="activity-icon">{{ event_icons.get(e.event_type, '•') }}</span>
+                <div class="activity-text">
+                    <a href="/board/{{ e.repo_full_name }}">{{ e.repo_full_name }}</a>
+                    <strong>#{{ e.issue_number }}</strong>
+                    {% if e.event_type == 'created' %}
+                        créée{% if e.to_column %} dans {{ column_labels.get(e.to_column, e.to_column) }}{% endif %}
+                    {% elif e.event_type == 'moved' %}
+                        déplacée{% if e.from_column %} de {{ column_labels.get(e.from_column, e.from_column) }}{% endif %} vers {{ column_labels.get(e.to_column, e.to_column) }}
+                    {% elif e.event_type == 'closed' %}
+                        fermée{% if e.source == 'gitea' %} (dans Gitea){% endif %}
+                    {% elif e.event_type == 'reopened' %}
+                        rouverte vers {{ column_labels.get(e.to_column, e.to_column) }}
+                    {% elif e.event_type == 'commented' %}
+                        commentée
+                    {% endif %}
+                    <span class="activity-date">{{ e.created_at[:16].replace('T', ' ') }}</span>
+                </div>
+            </div>
+            {% endfor %}
+        </div>
+    </main>
+
+    <footer>
+        Kanbante v{{ version }} · journal d'événements
+    </footer>
+</body>
+</html>

app/templates/board.html

@@ -8,6 +8,8 @@
     <link rel="stylesheet" href="/static/css/style.css">
     <script src="/static/vendor/htmx.min.js"></script>
     <script src="/static/vendor/sortable.min.js"></script>
+    <script src="/static/vendor/marked.min.js"></script>
+    <script src="/static/vendor/purify.min.js"></script>
     <script src="/static/js/board.js" defer></script>
 </head>
 <body>
@@ -19,6 +21,7 @@
         </h1>
         <nav>
             <a href="/focus" class="btn-sm">🎯 Focus</a>
+            <a href="/activity" class="btn-sm">📰 Activité</a>
             {% if repo_info.html_url %}
             <a href="{{ repo_info.html_url }}" target="_blank" class="btn-sm">🔗 Gitea</a>
             {% endif %}
@@ -48,7 +51,9 @@
                  data-column="{{ col }}">
                 <div class="column-header" style="border-top: 3px solid {{ column_colors[col] }}">
                     <span class="column-title">{{ column_labels[col] }}</span>
-                    <span class="column-count">{{ columns[col]|length }}</span>
+                    {% set limit = wip_limits.get(col) %}
+                    <span class="column-count{% if limit and columns[col]|length > limit %} over{% endif %}"
+                          {% if limit %}data-limit="{{ limit }}" title="Limite WIP : {{ limit }}"{% endif %}>{% if limit %}{{ columns[col]|length }}/{{ limit }}{% else %}{{ columns[col]|length }}{% endif %}</span>
                 </div>
                 <div class="column-cards" data-column="{{ col }}">
                     {% for issue in columns[col] %}
@@ -78,6 +83,11 @@
                             <img src="{{ issue.assignee.avatar_url }}" class="avatar" alt="{{ issue.assignee.login }}">
                             {% endif %}
                             <span class="card-date">{{ issue.created_at[:10] }}</span>
+                            {% set age = ages.get(issue.number) %}
+                            {% if age and age.days >= aging_days %}
+                            <span class="age-badge{% if age.days >= aging_days * 2 %} stale{% endif %}"
+                                  title="Dans cette colonne depuis le {{ age.since[:10] }}">⏳ {{ age.days }} j</span>
+                            {% endif %}
                         </div>
                     </div>
                     {% endfor %}
@@ -100,6 +110,28 @@
         </aside>
     </main>
 
+    <!-- Card detail drawer: issue body, comments, comment form -->
+    <div id="detail-overlay" class="detail-overlay" hidden></div>
+    <aside id="card-detail" class="card-detail" hidden>
+        <div class="detail-head">
+            <span id="detail-number" class="card-id"></span>
+            <span id="detail-state" class="chip"></span>
+            <button id="detail-close" class="btn-sm" type="button">✕</button>
+        </div>
+        <h2 id="detail-title"></h2>
+        <div id="detail-meta" class="detail-meta"></div>
+        <div id="detail-labels" class="card-labels"></div>
+        <div id="detail-body" class="detail-body"></div>
+        <h3 class="detail-comments-title">💬 Commentaires</h3>
+        <div id="detail-comments"></div>
+        <form id="comment-form">
+            <textarea id="comment-body" rows="3" maxlength="10000"
+                      placeholder="Écrire un commentaire (markdown)..."></textarea>
+            <button type="submit" class="btn-save">💬 Commenter dans Gitea</button>
+        </form>
+        <p class="detail-foot"><a id="detail-gitea-link" href="#" target="_blank">Ouvrir dans Gitea ↗</a></p>
+    </aside>
+
     <footer>
         <span>{{ full_name }}</span>
         {% if repo_info.updated_at %}

app/templates/dashboard.html

@@ -13,6 +13,7 @@
         <h1><a href="/">📋 <span class="gradient-text">Kanbante</span></a></h1>
         <nav>
             <a href="/focus" class="btn-sm">🎯 Focus</a>
+            <a href="/activity" class="btn-sm">📰 Activité</a>
             <span class="badge">{{ active_repos|length }} actifs</span>
             <span class="badge secondary">{{ archived_repos|length }} archivés</span>
         </nav>