feat(thickness): single Char range field — drop fp.recipe.thickness picker

Per client direction: every order is a thickness RANGE (e.g.
"0.0005-0.0008 mils" or "5-10 mils"), never a single value. The
old picker model (fp.recipe.thickness with a single 'value' Float)
was modelling the wrong concept and overcrowding the order entry
UI. Replaced with one free-text Char field that auto-fills from
last-used or part default.

DELETED entirely:
- fp.recipe.thickness model (file + view + ACL + manifest entry)
- recipe.thickness_option_ids One2many (the picker source)
- "Thickness Options" inline list on the recipe form
- sale.order.line.x_fc_thickness_id (M2O picker)
- account.move.line.x_fc_thickness_id
- fp.delivery.x_fc_thickness_id
- fp.direct.order.line.thickness_id

ADDED:
- sale.order.line.x_fc_thickness_range (Char) — operator types range
- account.move.line.x_fc_thickness_range — for invoice rendering
- fp.delivery.x_fc_thickness_range — for packing slip
- fp.direct.order.line.thickness_range — for the wizard
- fp.part.catalog.x_fc_default_thickness_range — part default

AUTO-FILL CHAIN (sale.order.line + wizard line):
1. Operator already typed → keep
2. Most recent SO line for (this part, this customer) with a
   non-empty thickness_range → copy that
3. part.x_fc_default_thickness_range → copy
4. Blank — operator types

Implemented as both an @api.onchange (interactive) AND a
create() override (programmatic — wizard, sale_mrp bridge,
imports). Same logic in both paths.

WIZARD push-to-defaults: when "Save as Default" toggle is ticked
on a wizard line, persist the line's thickness_range to
part.x_fc_default_thickness_range so future first-customer orders
get a sensible starting point.

REPORTS: customer_line_header.xml + report_fp_wo_sticker.xml now
print the Char range as-typed (no display_name lookup needed).

KEPT (admin documentation only — doesn't affect order entry):
- recipe.thickness_min, thickness_max, thickness_uom on the recipe
  root: documents the recipe's CAPABILITY range. No UI gate; just
  for spec authors to record what the chemistry can produce.

JOB GROUPING: fp.job auto-create groups SO lines by (recipe, part,
spec, thickness, serial). Updated to key on the thickness_range
Char (stripped) instead of the deleted thickness_id integer.

DB cleanup: --update=base ran on the upgrade, dropping the
fp_recipe_thickness table + the four x_fc_thickness_id columns.
Existing data was already nulled in earlier dev work.

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

fusion_plating/fusion_plating_configurator/views/fp_part_catalog_views.xml

@@ -203,11 +203,16 @@
                             </field>
                             <!-- Default Specification picker added by
                                  fusion_plating_quality view inherit. -->
+                            <separator string="Default Thickness" class="mt-4"/>
+                            <group>
+                                <field name="x_fc_default_thickness_range"
+                                       placeholder="e.g. 0.0005-0.0008 mils"/>
+                            </group>
                             <p class="text-muted">
-                                Set a Default Specification on this part
-                                (under the section added by the Quality
-                                module) so future direct-order lines
-                                pre-fill it automatically.
+                                Defaults pre-fill new direct-order lines
+                                for this part. Thickness also auto-fills
+                                from the most recent order for the same
+                                (part, customer) pair when one exists.
                             </p>
                         </page>
                         <page string="Dimensions &amp; Complexity" name="dimensions">

fusion_plating/fusion_plating_configurator/views/sale_order_views.xml

@@ -118,7 +118,7 @@
                            readonly="1">
                         <list create="false" delete="false" edit="false">
                             <field name="x_fc_part_catalog_id"/>
-                            <field name="x_fc_thickness_id" optional="show"/>
+                            <field name="x_fc_thickness_range" optional="show"/>
                             <field name="x_fc_process_variant_id" optional="show"
                                    string="Process"/>
                             <field name="product_uom_qty" string="Qty"/>
@@ -260,11 +260,8 @@
                        widget="boolean_toggle"
                        invisible="not x_fc_process_variant_id"
                        optional="hide"/>
-                <field name="x_fc_thickness_id"
-                       options="{'no_quick_create': True}"
-                       context="{'default_recipe_id': x_fc_process_variant_id}"
-                       domain="[('recipe_id', '=', x_fc_process_variant_id)]"
-                       invisible="not x_fc_process_variant_id"
+                <field name="x_fc_thickness_range"
+                       placeholder="e.g. 0.0005-0.0008 mils"
                        optional="show"/>
                 <field name="x_fc_serial_ids"
                        widget="many2many_tags"