feat(sub12b): fp.rack.tag — rack-label registry + 4 starter tags

M2M tag registry: Rush / Hold for QC / Damaged / Customer Sample.
Each rack can carry many tags; tags surface as coloured chips on the
plant-overview rack rows + Move Rack dialog (Task 13).

Plating → Configuration → Rack Tags menu (sequence 48).
post_init_hook seeds 4 starters — idempotent (no-op if any exist).

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

fusion_plating/fusion_plating/views/fp_rack_tag_views.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+    Copyright 2026 Nexa Systems Inc.
+    License OPL-1 (Odoo Proprietary License v1.0)
+    Part of the Fusion Plating product family.
+-->
+<odoo>
+
+    <record id="view_fp_rack_tag_list" model="ir.ui.view">
+        <field name="name">fp.rack.tag.list</field>
+        <field name="model">fp.rack.tag</field>
+        <field name="arch" type="xml">
+            <list string="Rack Tags" editable="bottom">
+                <field name="sequence" widget="handle"/>
+                <field name="name"/>
+                <field name="color" widget="color_picker"/>
+                <field name="active" widget="boolean_toggle"/>
+            </list>
+        </field>
+    </record>
+
+    <record id="action_fp_rack_tag" model="ir.actions.act_window">
+        <field name="name">Rack Tags</field>
+        <field name="res_model">fp.rack.tag</field>
+        <field name="view_mode">list</field>
+    </record>
+
+    <menuitem id="menu_fp_rack_tags"
+              name="Rack Tags"
+              parent="menu_fp_config"
+              action="action_fp_rack_tag"
+              sequence="48"/>
+
+</odoo>