chore(fusion_plating): add story-driven demo seeder + polish invoice PAID stamp

Demo seeder (scripts/fp_demo_seed.py):
- Idempotent Python script run via odoo shell; populates ~60 records
  across 6 customer stories covering every workflow state for live demo
- Customers: Amphenol (net-terms, deep history), Magellan (progress
  billing, active), Cyclone (deposit, in-production), Honeywell
  (net-terms, just confirmed), Westin (COD, direct-order path),
  Delinquent Industries (account hold — Confirm raises UserError)
- Coating configs with realistic AMS specs (2404, 2700 Rev G, 2406)
  and bake-relief flags set on applicable processes
- Part catalog with revision chains (Rev 1 / Rev 2 / Rev 3 for hot parts)
- Customer price lists with volume tiers
- Per-customer invoice strategy defaults
- Bath chemistry logs (15 readings, last 2 OOS → pending replenishment
  suggestion visible in menu)
- Racks: 4 active + 1 needing strip (MTO 3.2 / 3.0) for kanban demo
- Bake windows: 1 awaiting (ticking down), 1 baked, 1 missed (alert)
- Quote configurator sessions: 3 draft, 3 confirmed/won, 3 lost (with
  reasons), 1 expired — populates the win/loss analysis
- Historical closed orders: 8 jobs backdated across 4 months with
  SO → MO → Delivery → Invoice → Payment run through each hook so
  portal-job progression, certificates with thickness readings, and
  invoice AR aging all look real
- Active orders at every workflow stage for the live demo cycle

Polish:
- report_fp_invoice PAID stamp now also triggers on payment_state ==
  'in_payment' (in addition to 'paid'). Odoo leaves payments in
  'in_payment' until the bank reconciliation job matches them against
  a statement line, so historical demo invoices would otherwise never
  show as stamped even though the payment is posted and the customer
  owes nothing.

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

fusion_plating/fusion_plating_reports/report/report_fp_invoice.xml

@@ -173,7 +173,7 @@
                             </div>
 
                             <!-- Paid stamp -->
-                            <t t-if="doc.payment_state == 'paid'">
+                            <t t-if="doc.payment_state in ('paid', 'in_payment')">
                                 <div style="margin-top: 15px; text-align: center;">
                                     <span class="paid-stamp">PAID</span>
                                 </div>
@@ -364,7 +364,7 @@
                             </div>
 
                             <!-- Paid stamp -->
-                            <t t-if="doc.payment_state == 'paid'">
+                            <t t-if="doc.payment_state in ('paid', 'in_payment')">
                                 <div style="margin-top: 15px; text-align: center;">
                                     <span class="paid-stamp">PAID</span>
                                 </div>
@@ -378,7 +378,7 @@
                                         <thead>
                                             <tr>
                                                 <th colspan="3" style="background-color: #28a745; color: white;">
-                                                    <t t-if="doc.payment_state == 'paid'">✓ PAYMENT DETAILS — PAID IN FULL</t>
+                                                    <t t-if="doc.payment_state in ('paid', 'in_payment')">✓ PAYMENT DETAILS — PAID IN FULL</t>
                                                     <t t-elif="doc.payment_state == 'partial'">PAYMENT DETAILS — PARTIALLY PAID</t>
                                                     <t t-else="">PAYMENT DETAILS</t>
                                                 </th>