feat(v4.2.0): Database Templates & Dashboards

- Enhance page_templates: add description, is_recurring, recurrence_rule columns
- New table collection_dashboards for widget-based dashboard layouts
- API: PUT/DELETE /workspace/collections/{id}/templates/page/{tid} — template CRUD
- API: CRUD /workspace/collections/{id}/dashboards (create/list/update/delete)
- Dashboard layout_json supports columns + widgets with view_id/x/y/w/h
- 6 new tests (159 total)

app/db.py

@@ -487,6 +487,34 @@ def init_db():
             pass
         conn.commit()
 
+        # v4.2.0: Collection Templates (enhanced) + Dashboards
+        # Add description, is_recurring, recurrence_rule to page_templates
+        try:
+            conn.execute("ALTER TABLE page_templates ADD COLUMN description TEXT DEFAULT ''")
+        except sqlite3.OperationalError:
+            pass
+        try:
+            conn.execute("ALTER TABLE page_templates ADD COLUMN is_recurring BOOLEAN NOT NULL DEFAULT 0")
+        except sqlite3.OperationalError:
+            pass
+        try:
+            conn.execute("ALTER TABLE page_templates ADD COLUMN recurrence_rule TEXT DEFAULT ''")
+        except sqlite3.OperationalError:
+            pass
+
+        # Dashboard: combinaison de vues/widgets sur une page
+        conn.execute("""
+            CREATE TABLE IF NOT EXISTS collection_dashboards (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                collection_id INTEGER NOT NULL REFERENCES collections(id) ON DELETE CASCADE,
+                name TEXT NOT NULL DEFAULT 'Dashboard',
+                layout_json TEXT NOT NULL DEFAULT '{"columns":1,"widgets":[]}',
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+                updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+            )
+        """)
+        conn.commit()
+
 
 @contextmanager
 def get_conn():