feat(bridge_mrp): SO workflow stage + contextual buttons (CHUNK 3/4)

Sale Order form now guides the user through the next step without
making them navigate between screens.

New computed field sale.order.x_fc_workflow_stage with 12 stages:
  draft → awaiting_parts → inspecting → accept_parts → assign_work
       → in_production → ready_to_ship → shipped → invoicing
       → paid → complete (+ cancelled)

Driven by SO.state + x_fc_receiving_status + MO state +
delivery.state + invoice payment state.

Five contextual header buttons (only 1-2 visible at any time,
fusion_claims pattern — invisible="x_fc_workflow_stage != 'foo'"):

  Mark Inspecting       → flips receiving to 'inspecting'
  Accept Parts          → flips receiving to 'accepted' + SO status
                          to 'inspected', unlocks manager assignment
  Assign To Me & Release → manager claims the job, confirms all draft
                          MOs (which auto-generates WOs already)
  Open Shop Floor       → jumps to Plant Overview during production
  Mark Shipped          → closes open delivery records → triggers
                          auto-invoice per strategy

Info banner shows current stage + assigned manager on the sheet so
users always know where they are.

New fields:
  sale.order.x_fc_assigned_manager_id (Many2one res.users, tracked)
  mrp.production.x_fc_assigned_manager_id (Many2one, propagated on
                                           MO confirm)

MO.action_confirm() now pulls the assigned manager from the SO (or
falls back to SO.user_id) and sets it on the MO — sets up the
Manager Dashboard (chunk 2) and role-based assignment (chunk 4) to
filter "my jobs" cleanly.

Smoke-tested across 10 demo SOs — stages compute correctly:
  S00028 → ready_to_ship, S00027-25 → awaiting_parts,
  S00023-20 → complete/shipped, S00029 → draft.

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

fusion_plating/fusion_plating_bridge_mrp/views/sale_order_views.xml

@@ -52,6 +52,62 @@
                            string="Deliveries"/>
                 </button>
             </xpath>
+
+            <!-- ===== Contextual workflow buttons on the header =====
+                 One (sometimes two) visible at a time. Pattern mirrors
+                 fusion_claims ADP handling — invisible bindings key off
+                 the computed x_fc_workflow_stage selector.            -->
+            <xpath expr="//header" position="inside">
+                <field name="x_fc_workflow_stage" invisible="1"/>
+                <field name="x_fc_assigned_manager_id" invisible="1"/>
+
+                <button name="action_fp_mark_inspected"
+                        string="Mark Inspecting" type="object"
+                        class="btn-primary" icon="fa-search"
+                        invisible="x_fc_workflow_stage != 'inspecting'"
+                        help="Move receiving record(s) into the Inspecting state."/>
+
+                <button name="action_fp_accept_parts"
+                        string="Accept Parts" type="object"
+                        class="btn-primary" icon="fa-check"
+                        invisible="x_fc_workflow_stage not in ('inspecting', 'accept_parts')"
+                        help="Parts pass inspection — ready for assignment."/>
+
+                <button name="action_fp_assign_to_me"
+                        string="Assign To Me &amp; Release" type="object"
+                        class="btn-primary" icon="fa-user-plus"
+                        invisible="x_fc_workflow_stage != 'assign_work'"
+                        help="Take ownership as manager and release MOs to the shop floor."/>
+
+                <button name="action_fp_open_shop_floor"
+                        string="Open Shop Floor" type="object"
+                        class="btn-secondary" icon="fa-industry"
+                        invisible="x_fc_workflow_stage != 'in_production'"
+                        help="Jump to the Plant Overview to watch production."/>
+
+                <button name="action_fp_mark_shipped"
+                        string="Mark Shipped" type="object"
+                        class="btn-success" icon="fa-truck"
+                        invisible="x_fc_workflow_stage != 'ready_to_ship'"
+                        help="Close the open delivery record(s) and fire auto-invoice per strategy."/>
+            </xpath>
+
+            <!-- Show the workflow stage on the sheet so users always
+                 know what step they're on (readonly banner). -->
+            <xpath expr="//sheet" position="inside">
+                <div class="alert alert-info mb-2"
+                     style="border-radius: 6px;"
+                     invisible="x_fc_workflow_stage in ('draft', 'complete', 'cancelled')">
+                    <i class="fa fa-compass me-2"/>
+                    <strong>Current stage:</strong>
+                    <field name="x_fc_workflow_stage" readonly="1" nolabel="1" class="ms-1"/>
+                    <span class="ms-3 text-muted"
+                          invisible="not x_fc_assigned_manager_id">
+                        · Assigned to
+                        <field name="x_fc_assigned_manager_id" readonly="1" nolabel="1" class="ms-1"/>
+                    </span>
+                </div>
+            </xpath>
         </field>
     </record>