Add pagination, device detail unassign-all, and batch install with slot limit

app.py

@@ -958,8 +958,45 @@ def create_app(config_object="config"):
             f"Unassigned {count} batter{'y' if count == 1 else 'ies'} from {device.name}.",
             "success",
         )
+        nxt = request.form.get("next", "")
+        if nxt.startswith("/"):
+            return redirect(nxt)
         return redirect(url_for("device_list"))
 
+    # ------------------------------------------------------------------ #
+    # Devices — batch install specific batteries
+    # ------------------------------------------------------------------ #
+
+    @app.route("/device/<int:device_id>/install-batch", methods=["POST"])
+    def device_install_batch(device_id):
+        device = db.get(Device, device_id)
+        if device is None:
+            abort(404)
+        battery_ids = request.form.getlist("battery_ids")
+        free = device.battery_slots - device.installed_count()
+        if not battery_ids:
+            flash("No batteries selected.", "warning")
+            return redirect(url_for("device_detail", device_id=device_id))
+        installed = 0
+        for bid in battery_ids:
+            if installed >= free:
+                break
+            battery = db.get(Battery, int(bid))
+            if not battery or battery.status != "available":
+                continue
+            battery.status = "installed"
+            battery.device_id = device.id
+            installed += 1
+        db.commit()
+        if installed:
+            flash(
+                f"Installed {installed} batter{'y' if installed == 1 else 'ies'} into {device.name}.",
+                "success",
+            )
+        else:
+            flash("No batteries were installed.", "warning")
+        return redirect(url_for("device_detail", device_id=device_id))
+
     # ------------------------------------------------------------------ #
     # Export
     # ------------------------------------------------------------------ #