fix(fusion_repairs): code-review batch - 4 critical + 8 high + 8 medium/low

Critical
- C1: _sql_constraints -> models.Constraint (Odoo 19 deprecation rule violation)
- C2: variance threshold no longer uses abs() - under-cost is good news,
  must not block invoicing. Now only OVER-cost triggers requires_requote.
- C3: roll_next_due_date() was dead code - now wired from
  fusion.technician.task.write() when a maintenance task transitions to
  'completed', so the whole maintenance lifecycle actually advances.
- C4: warranty.is_active was store=True but time-dependent (became stale).
  Dropped store=True; find_active_for() now filters by expiry_date directly.

High
- H1: added x_fc_maintenance_contract_id back-link on repair.order and
  populated it from create_repair_from_booking().
- H2: find_active_for() returns empty when neither lot nor product is
  supplied - prevents cross-product false warranty matches.
- H3: visit-report wizard now creates stock.move records of repair_line_type
  'add' for each part line, so Odoo's native action_create_sale_order()
  chain has lines to invoice and stock gets consumed properly.
- H4: office intake email template now carries a fallback email_to header
  computed from res.company.x_fc_office_notification_ids (or company email),
  so it does not silently send with no recipient.
- H5: maintenance reminder cron nextcall now always rolls to tomorrow
  at 07:00 local time, so installing/upgrading after 07:00 does not
  immediately fire all the day's reminders.
- H6: public portal no longer hardcodes UID 1 as the intake user fallback
  (which in Odoo 19 is OdooBot). Prefers base.user_admin, else the
  lowest-id non-share user, else SUPERUSER_ID.
- H7: public portal validates client_email via tools.email_normalize
  before partner creation; malformed addresses redirect with error=email.
- H8: find_best_match() returns empty when no symptom keywords match
  (no silent first-catalog guess) and uses word-boundary regex to avoid
  matching 'battery' inside 'no battery problem'.

Medium
- M1: _inherit moved next to _name on maintenance_contract (cosmetic but
  brittle if Odoo refactors model class detection)
- M2: relativedelta(months=N) instead of timedelta(days=N*30) for warranty
  and maintenance intervals (correct month boundaries)
- M3: unique constraint on fusion.repair.maintenance.contract.booking_token
- M6: dispatch task fallback now searches for an actual x_fc_is_field_staff
  user; gracefully skips and logs if no field staff exists (instead of
  silently failing the constraint check)
- M7: maintenance contract list view date decoration uses context_today()
  (date) instead of strftime(string) - the str comparison would TypeError
- M9: Visit Report button hidden on draft repairs and when no technician
  task is linked yet

Low
- L2: portal-created partners get default lang + company_id so mail
  templates render in the right language
- L3: dropped unused exception variable in sales rep portal controller
- L4: visit-report wizard 'found another issue' now redirects to the
  spawned stub repair so the tech can fill it in immediately
- L5: dropped unrecognized data-string from <app> in settings view

Public portal also: rate-limit check moved BEFORE the counter increment so
blocked attempts do not keep inflating the bucket.

All fixes verified end-to-end on local westin-v19:
- variance one-sided: 0.5h labour vs $500 est -> requires_requote=False;
  2h x $250 + $200 parts vs $100 est -> requires_requote=True
- maintenance roll-forward: created MC/00006 due 2026-05-31, completed
  linked maintenance task -> contract rolled to 2026-11-21 with
  last_reminder_band reset
- warranty find_active_for(partner only) -> empty recordset
- service catalog find_best_match with unrelated text -> empty recordset
- pg_constraint shows fusion_repair_maintenance_contract_booking_token_unique
- /repair landing still 200 after restart

Co-authored-by: Cursor <cursoragent@cursor.com>

fusion_repairs/views/maintenance_contract_views.xml

@@ -5,7 +5,7 @@
         <field name="name">fusion.repair.maintenance.contract.list</field>
         <field name="model">fusion.repair.maintenance.contract</field>
         <field name="arch" type="xml">
-            <list string="Maintenance Contracts" decoration-warning="next_due_date and next_due_date &lt;= context_today().strftime('%Y-%m-%d')">
+            <list string="Maintenance Contracts" decoration-warning="next_due_date and next_due_date &lt;= context_today()">
                 <field name="name"/>
                 <field name="partner_id"/>
                 <field name="product_id"/>

fusion_repairs/views/repair_order_views.xml

@@ -16,7 +16,7 @@
                         type="object"
                         string="Visit Report"
                         class="btn-primary"
-                        invisible="state == 'cancel'"
+                        invisible="state in ('draft', 'cancel') or x_fc_technician_task_count == 0"
                         groups="fusion_repairs.group_fusion_repairs_user"/>
                 <button name="action_collect_payment"
                         type="object"

fusion_repairs/views/res_config_settings_views.xml

@@ -7,8 +7,7 @@
         <field name="inherit_id" ref="base.res_config_settings_view_form"/>
         <field name="arch" type="xml">
             <xpath expr="//form" position="inside">
-                <app data-string="Fusion Repairs"
-                     string="Fusion Repairs"
+                <app string="Fusion Repairs"
                      name="fusion_repairs"
                      groups="fusion_repairs.group_fusion_repairs_manager">
                     <block title="Notifications" name="fc_repairs_notifications">