fusion_authorizer_portal: wire accessibility assessments into MOD/ODSP/WSIB workflows (v19.0.2.8.0)

Audit found that fusion.accessibility.assessment._create_draft_sale_order
hardcoded x_fc_sale_type='direct_private' for ALL accessibility cases —
meaning MOD, ODSP, WSIB, and insurance projects never entered their
respective downstream workflows. The MOD workflow rework I shipped in
fusion_claims 19.0.8.0.3 was effectively unreachable from the portal.

Also: x_fc_authorizer_id never propagated from the assessment to the SO,
the new x_fc_mod_accessibility_specialist_id was orphaned, and there
was no back-reference from sale.order to the accessibility assessment.

Fixes:
- New required field x_fc_funding_source on fusion.accessibility.assessment
  (march_of_dimes / odsp / wsib / insurance / direct_private / other)
- _create_draft_sale_order now maps funding_source -> x_fc_sale_type,
  copies authorizer_id -> x_fc_authorizer_id, sets accessibility_assessment_id
  back-ref, and for MOD cases pre-populates
  x_fc_mod_accessibility_specialist_id from sales_rep_id.partner_id
- New accessibility_assessment_id field on sale.order so the back-link
  is queryable both directions (previously only assessment->SO existed)
- action_complete now guards against double-completion and missing
  funding_source: raises UserError instead of silently creating duplicates
- Expanded fusion.accessibility.assessment.state from 3 to 6 values
  (draft/scheduled/in_progress/pending_review/completed/cancelled),
  added copy=False, added _expand_states group_expand for kanban
- Booking form at /book-assessment now collects funding_source
  (required dropdown) so the path is known before the visit happens
- portal_assessment.py book_assessment_submit accepts funding_source
  with whitelist validation (defaults to direct_private if missing)

Deployed to odoo-westin (westin-v19) and odoo-mobility (mobility),
both verified at v19.0.2.8.0 with the new columns present.

fusion_authorizer_portal/models/sale_order.py

@@ -33,12 +33,25 @@ class SaleOrder(models.Model):
         compute='_compute_portal_document_count',
     )
     
-    # Link to assessment
+    # Link to assessment (ADP equipment assessment — rollators, wheelchairs, powerchairs)
     assessment_id = fields.Many2one(
         'fusion.assessment',
-        string='Source Assessment',
+        string='Source ADP Assessment',
         readonly=True,
-        help='The assessment that created this sale order',
+        help='The ADP equipment assessment that created this sale order',
+    )
+
+    # 2026-04 portal audit fix — link to the accessibility (modification)
+    # assessment if this sale order came from a stair lift / VPL / ceiling lift
+    # / ramp / bathroom modification / tub cutout visit. Previously there
+    # was no way to trace a MOD/ODSP sale order back to its source assessment.
+    accessibility_assessment_id = fields.Many2one(
+        'fusion.accessibility.assessment',
+        string='Source Accessibility Assessment',
+        readonly=True,
+        help='The accessibility (modification) assessment that created this '
+             'sale order — stair lift, VPL, ceiling lift, ramp, bathroom mod, '
+             'or tub cutout visits.',
     )
     
     # Authorizer helper field (consolidates multiple possible fields)