feat(fp.job): button_mark_shipped + milestone cascade integration (Task 5)

button_mark_shipped: manual transition awaiting_ship → done. Does
not re-run the bake/qty/QC gates — those passed at the in_progress
→ awaiting_cert/ship transition. Just the 'yes, shipped' stamp.

Milestone cascade (_compute_next_milestone_action) extended to
recognize the two new states:
  - awaiting_cert → 'issue_certs' button
  - awaiting_ship → 'mark_shipped' button
Legacy state='done' branch preserved for historical jobs.

action_advance_next_milestone now dispatches 'mark_shipped' via
_action_mark_shipped_dispatch which routes:
  awaiting_ship → button_mark_shipped (new path)
  done + active delivery → _action_mark_active_delivery_delivered
    (legacy, unchanged)

View: 'Mark Shipped' milestone button gated on Manager/Owner groups.

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

fusion_plating/fusion_plating_jobs/views/fp_job_form_inherit.xml

@@ -68,7 +68,8 @@
                         string="Mark Shipped"
                         class="btn-success"
                         icon="fa-paper-plane"
-                        invisible="next_milestone_action != 'mark_shipped'"/>
+                        invisible="next_milestone_action != 'mark_shipped'"
+                        groups="fusion_plating.group_fp_manager,fusion_plating.group_fp_owner"/>
                 <field name="all_steps_terminal" invisible="1"/>
                 <field name="next_milestone_action" invisible="1"/>
                 <button name="action_print_sticker" type="object"