[IMP] maintenance_service_http_monitoring: auto-close request on service recovery

Previously, maintenance requests created on HTTP failures were never
automatically resolved. Operators had to close them manually, with no
traceability of when or why the request was closed.

This commit adds automatic resolution when a service returns HTTP 200
while an open maintenance request exists for it.

**Detection logic** (in ``cron_check_http_services``):

Before pass 1, the cron takes a snapshot of all services that currently
have an open (non-done) ``maintenance.request`` via
``http_maintenance_request``. After pass 1, services in that snapshot
that are now OK (``http_status_ok = True``) are identified as recovered
and passed to the new ``_close_http_maintenance_request()`` method.

**Closure logic** (new ``_close_http_maintenance_request`` method):

1. Finds the first ``maintenance.stage`` with ``done = True``.
   If none exists (misconfigured instance), the method is a no-op.
2. Moves the ``maintenance.request`` to that done stage via ``sudo()``
   to bypass ACL restrictions from the cron user context.
3. Posts a chatter note on the request as OdooBot (``base.partner_root``)
   using ``subtype_xmlid="mail.mt_note"`` (internal note, not a follower
   notification) indicating the service URL and that the closure was
   performed automatically by the monitoring cron.
4. Clears ``http_maintenance_request`` on the ``service.instance``,
   allowing a fresh request to be created if the service fails again.

**Tests** (2 new, 16 total):

- ``test_service_recovery_closes_request``: full end-to-end scenario —
  first cron run produces a KO request, second cron run with HTTP 200
  asserts the request is in a done stage, the chatter note mentioning
  the service URL exists, and ``http_maintenance_request`` is cleared.
- ``test_no_close_when_no_open_request``: calling
  ``_close_http_maintenance_request`` on a service with no open request
  is a no-op and does not raise.

**README**: "Automatic Maintenance Requests" section extended with the
recovery behaviour (done stage, OdooBot note, field cleared).

maintenance_service_http_monitoring/tests/test_http_monitoring.py

@@ -312,3 +312,49 @@ class TestHttpMonitoring(TransactionCase):
             ),
             2,
         )
+
+    # ------------------------------------------------------------------
+    # Test 15 -- Service recovery closes the open request and posts a note
+    # ------------------------------------------------------------------
+    def test_service_recovery_closes_request(self):
+        # First cron run: service is KO -> request created
+        with (
+            patch(SERVICE_INSTANCE_REQUESTS) as mock_requests,
+            patch(SERVICE_INSTANCE_SLEEP),
+        ):
+            mock_requests.get.return_value = _mock_response(500)
+            mock_requests.exceptions.RequestException = Exception
+            self.env["service.instance"].cron_check_http_services()
+
+        request = self.service_instance.http_maintenance_request
+        self.assertTrue(request)
+        self.assertFalse(request.stage_id.done)
+
+        # Second cron run: service is back OK -> request auto-closed
+        with (
+            patch(SERVICE_INSTANCE_REQUESTS) as mock_requests,
+            patch(SERVICE_INSTANCE_SLEEP),
+        ):
+            mock_requests.get.return_value = _mock_response(200)
+            mock_requests.exceptions.RequestException = Exception
+            self.env["service.instance"].cron_check_http_services()
+
+        # Request must be in a done stage
+        self.assertTrue(request.stage_id.done)
+        # http_maintenance_request must be cleared on the service instance
+        self.assertFalse(self.service_instance.http_maintenance_request)
+        # A chatter note must have been posted mentioning the service URL
+        notes = request.message_ids.filtered(
+            lambda m: self.service_instance.service_url in (m.body or "")
+        )
+        self.assertTrue(notes)
+
+    # ------------------------------------------------------------------
+    # Test 16 -- No open request -> _close_http_maintenance_request is a no-op
+    # ------------------------------------------------------------------
+    def test_no_close_when_no_open_request(self):
+        # Service is OK from the start, no request exists
+        self.assertFalse(self.service_instance.http_maintenance_request)
+        # Calling close directly must not raise
+        self.service_instance._close_http_maintenance_request()
+        self.assertFalse(self.service_instance.http_maintenance_request)