fusion_plating: add process recipe system with OWL tree editor (v19.0.2.0.0)

New model fusion.plating.process.node with _parent_store hierarchy for
defining reusable plating recipes. Node types: recipe, sub_process,
operation, step. Includes companion model for operator input definitions.

Full OWL tree editor (client action) with:
- Hierarchical tree with connector lines and type-coloured borders
- Click-to-edit side panel with save
- Add/delete child nodes inline
- Drag & drop reorder and reparent
- Theme-aware SCSS (light + dark mode)
- Demo data: Electroless Nickel Plating — Steel Line (30+ nodes)

Backend: 7 JSON-RPC endpoints for tree CRUD, reorder, move, duplicate.
Security: 3-tier ACL (operator read / supervisor write / manager full).
Menu: Process Recipes under Plating > Operations.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fusion-plating/fusion_plating/models/__init__.py

@@ -12,4 +12,5 @@ from . import fp_bath
 from . import fp_bath_log
 from . import fp_bath_log_line
 from . import fp_bath_parameter
+from . import fp_process_node
 from . import res_company