fix(fusion_helpdesk): define missing _norm_email helper (NameError on every inbox endpoint)

The IDOR-hardening commit (fb345be3) referenced _norm_email in submit()
and _identity() but never defined or imported it, so every inbox endpoint
(my_tickets, ticket_detail, ticket_reply, unread_count) and the New-ticket
submit path raised NameError at runtime — surfaced as a JSON-RPC error in
the dialog. The smoke test missed it because it replicated build_scope_domain
directly instead of calling the controller.

Add _norm_email(*candidates) to utils.py (returns the first candidate that
email_normalize accepts, else '' — rejecting self-set wildcards like '%' so
the inbox scope key can't be widened), import it in main.py, drop the now-unused
email_normalize import there, and add unit tests + a guard that the controller
namespace resolves the name.

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

fusion_helpdesk/__manifest__.py

@@ -3,7 +3,7 @@
 # License OPL-1 (Odoo Proprietary License v1.0)
 {
     'name': 'Fusion Helpdesk Reporter',
-    'version': '19.0.1.4.0',
+    'version': '19.0.1.4.1',
     'category': 'Productivity',
     'summary': 'One-click in-app bug reporting & feature requesting — '
                'auto-creates a helpdesk.ticket on a central Odoo Helpdesk.',