fix: rename ambiguous 'Work Center' / 'Work Centres' menus

Two distinct entities were both labelled 'Work Centre' (US/UK spelling
the only differentiator — confusing). Renamed by purpose, model IDs
unchanged so all 12+9 existing cross-refs keep working:

fusion.plating.work.center → 'Production Line'
  Physical shop-layout grouping that owns tanks. Examples: 'Line 1 —
  EN', 'Anodize Line', 'Prep Bay'. Has tank_ids (O2M),
  supported_process_ids (M2M), capacity_per_day. The thing tanks live
  in.

fp.work.centre → 'Routing Station'
  Per-job-step routing entity (post-Sub-11 mrp.workcenter replacement).
  Has 'kind' selection (wet_line / bake / mask / rack / inspect),
  cost_per_hour for fp.job.step rollup, default_bath_id +
  default_tank_id for release-ready validation. The thing a job step
  routes through.

Conceptually a Production Line CONTAINS many Routing Stations (e.g.
'EN Line' production line has wet-line, bake, inspect routing
stations on it).

Updated:
- _description on both models
- string= on the name fields
- list/form/search view strings
- act_window names ('Production Lines' / 'Routing Stations')
- menu items in fp_menu.xml + fp_jobs_menu.xml
- doc comments in both model files explaining the distinction

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

fusion_plating/fusion_plating/views/fp_jobs_menu.xml

@@ -5,10 +5,16 @@
          "All Jobs" and "Steps" used to live under a separate "Jobs"
          submenu but the user moved them under Shop Floor instead
          (see fusion_plating_jobs/views/jobs_in_shopfloor_menu.xml).
-         Only Work Centres stays in core (under Configuration). -->
+         Routing Stations stays in core (under Configuration → Shop Setup).
+
+         Note: this is the per-step routing entity (fp.work.centre,
+         post-Sub-11 mrp.workcenter replacement) — distinct from the
+         shop-layout 'Production Lines' (fusion.plating.work.center)
+         that group tanks. Routing Stations are kind-aware (wet_line /
+         bake / mask / rack / inspect) and carry cost_per_hour. -->
 
     <menuitem id="menu_fp_jobs_work_centres"
-              name="Work Centres"
+              name="Routing Stations"
               parent="menu_fp_config_shop_setup"
               action="action_fp_work_centre"
               sequence="25"

fusion_plating/fusion_plating/views/fp_menu.xml

@@ -140,7 +140,7 @@
               sequence="10"/>
 
     <menuitem id="menu_fp_work_centers"
-              name="Work Centers"
+              name="Production Lines"
               parent="menu_fp_config_shop_setup"
               action="action_fp_work_center"
               sequence="20"/>

fusion_plating/fusion_plating/views/fp_work_center_views.xml

@@ -10,7 +10,7 @@
         <field name="name">fp.work.center.list</field>
         <field name="model">fusion.plating.work.center</field>
         <field name="arch" type="xml">
-            <list string="Work Centers">
+            <list string="Production Lines">
                 <field name="facility_id"/>
                 <field name="sequence" widget="handle"/>
                 <field name="code"/>
@@ -26,7 +26,7 @@
         <field name="name">fp.work.center.form</field>
         <field name="model">fusion.plating.work.center</field>
         <field name="arch" type="xml">
-            <form string="Work Center">
+            <form string="Production Line">
                 <sheet>
                     <widget name="web_ribbon" title="Archived" bg_color="text-bg-danger" invisible="active"/>
                     <div class="oe_title">
@@ -70,7 +70,7 @@
         <field name="name">fp.work.center.search</field>
         <field name="model">fusion.plating.work.center</field>
         <field name="arch" type="xml">
-            <search string="Work Centers">
+            <search string="Production Lines">
                 <field name="name"/>
                 <field name="code"/>
                 <field name="facility_id"/>
@@ -83,7 +83,7 @@
     </record>
 
     <record id="action_fp_work_center" model="ir.actions.act_window">
-        <field name="name">Work Centers</field>
+        <field name="name">Production Lines</field>
         <field name="res_model">fusion.plating.work.center</field>
         <field name="view_mode">list,form</field>
         <field name="search_view_id" ref="view_fp_work_center_search"/>

fusion_plating/fusion_plating/views/fp_work_centre_views.xml

@@ -43,7 +43,7 @@
     </record>
 
     <record id="action_fp_work_centre" model="ir.actions.act_window">
-        <field name="name">Work Centres</field>
+        <field name="name">Routing Stations</field>
         <field name="res_model">fp.work.centre</field>
         <field name="view_mode">list,form</field>
     </record>