feat(fusion_helpdesk): customer follow-up + embedded ticket inbox

Squash-merge of feat/helpdesk-customer-followup. The billing and
fusion_login_audit work from that branch is already on main (landed
separately); this lands only the helpdesk feature.

- Identity keystone: submit() forwards partner_email/partner_name/
  x_fc_client_label so the central Helpdesk find-or-creates the customer
  partner and subscribes them as a follower (enables reply emails + magic link).
- Embedded in-app 'My Tickets' inbox: server-side scoped read/reply RPC
  endpoints, per-user seen tracking (fusion.helpdesk.ticket.seen), systray
  unread badge. Defense-in-depth scope domain + _norm_email normalisation
  (wildcard emails cannot widen scope).
- fusion_helpdesk_central: x_fc_client_label field + list/search views +
  branded acknowledgement email template.
- Deployed and smoke-tested live: nexa central 19.0.1.1.0, entech client
  19.0.1.4.1 (requires Contact Creation on the central service account).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion_helpdesk_central/tests/__init__.py

@@ -0,0 +1,2 @@
+# -*- coding: utf-8 -*-
+from . import test_identity

fusion_helpdesk_central/tests/test_identity.py

@@ -0,0 +1,68 @@
+# -*- coding: utf-8 -*-
+# Copyright 2026 Nexa Systems Inc.
+# License OPL-1
+"""Identity-keystone tests for the central helpdesk extensions.
+
+Runs on an Enterprise environment (helpdesk installed) — e.g. odoo-nexa or
+odoo-trial. Validates that passing partner_email resolves the customer +
+follower (native), that the client label is stored, and that the branded
+acknowledgement only fires for in-app-channel tickets.
+"""
+from odoo.tests import TransactionCase, tagged
+
+
+@tagged('post_install', '-at_install', 'fusion_helpdesk_central')
+class TestTicketIdentity(TransactionCase):
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.team = cls.env['helpdesk.team'].search([], limit=1)
+
+    def _ack_mails(self, ticket):
+        return self.env['mail.mail'].search([
+            ('model', '=', 'helpdesk.ticket'),
+            ('res_id', '=', ticket.id),
+        ]).filtered(lambda m: 'received your request' in (m.subject or ''))
+
+    def test_partner_resolution_follower_and_label(self):
+        ticket = self.env['helpdesk.ticket'].create({
+            'name': 'Keystone test',
+            'team_id': self.team.id,
+            'partner_email': 'keystone.newperson@example.com',
+            'partner_name': 'Key Stone',
+            'x_fc_client_label': 'ENTECH',
+        })
+        self.assertEqual(ticket.x_fc_client_label, 'ENTECH')
+        self.assertTrue(
+            ticket.partner_id,
+            "native create() should find-or-create a partner from partner_email")
+        self.assertEqual(ticket.partner_id.email, 'keystone.newperson@example.com')
+        self.assertIn(
+            ticket.partner_id, ticket.message_partner_ids,
+            "the customer must be subscribed as a follower")
+
+    def test_ack_email_for_inapp_ticket(self):
+        ticket = self.env['helpdesk.ticket'].create({
+            'name': 'Ack test',
+            'team_id': self.team.id,
+            'partner_email': 'ack.person@example.com',
+            'partner_name': 'Ack Person',
+            'x_fc_client_label': 'ENTECH',
+        })
+        self.assertTrue(
+            self._ack_mails(ticket),
+            "an in-app ticket with a customer email should get our ack email")
+
+    def test_no_ack_without_client_label(self):
+        # Simulates an external web-form ticket — no client label, so our
+        # acknowledgement must NOT fire (avoids double-acknowledgement).
+        ticket = self.env['helpdesk.ticket'].create({
+            'name': 'External web ticket',
+            'team_id': self.team.id,
+            'partner_email': 'external.web@example.com',
+            'partner_name': 'External Web',
+        })
+        self.assertFalse(
+            self._ack_mails(ticket),
+            "no client label => our acknowledgement should not send")