feat(fusion_planning): auto-publish new shifts + bulk-assign to many employees

Two manager-side time savers on the Add Shift dialog:

1. Auto-publish on create
   Override planning.slot.create() to default state='published' for
   every new shift (was: 'draft', requiring a separate Publish step
   per slot — painful with recurrence which can generate dozens at
   a time). Recurrency-generated copies inherit the parent slot's
   state, so a single recurring shift now publishes the whole series
   in one save. Manager can still pass state='draft' explicitly to
   opt out.

2. Apply Also To (multi-resource bulk create)
   New x_fc_additional_resource_ids m2m on planning.slot. When set,
   create() splits the vals into one slot per additional resource
   (deduped against the primary). Combined with recurrence, picking
   N employees and a date range now creates the full N x M shift
   matrix in a single Save instead of N manual repeats.

   Field appears in the Add Shift dialog under Role, hidden once
   the slot is saved (it's a create-time helper, not ongoing data),
   and gated to planning.group_planning_manager.

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

fusion_planning/views/planning_slot_views.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+
+    <!-- Add "Apply Also To" m2m field to the Add Shift dialog so a
+         manager can create the same shift for many employees in one save. -->
+    <record id="planning_view_form_inherit_fusion_planning" model="ir.ui.view">
+        <field name="name">planning.slot.form.inherit.fusion_planning</field>
+        <field name="model">planning.slot</field>
+        <field name="inherit_id" ref="planning.planning_view_form"/>
+        <field name="arch" type="xml">
+            <xpath expr="//field[@name='role_id']" position="after">
+                <field name="x_fc_additional_resource_ids"
+                       widget="many2many_tags"
+                       options="{'no_create': True, 'no_quick_create': True}"
+                       placeholder="Pick more employees to apply this shift to"
+                       invisible="id"
+                       groups="planning.group_planning_manager"/>
+            </xpath>
+        </field>
+    </record>
+
+</odoo>