feat(configurator): replace inline previews with smart button + Preview links

The Quote Configurator form devoted nearly half its width to a sticky
3D viewer + drawing PDF preview. That panel meant the actual fields
(geometry, dimensions, pricing) had to fight for real estate. Replaced
the inline previews with two affordances that take zero layout space:

  1. New '3D Model' smart button at the top of the form, next to the
     existing 'Drawings' button. Click to open the existing
     fp_3d_viewer_open client action — same fullscreen modal the
     'Full Screen' button used to launch from the side panel.

  2. Inline 'Preview' link (eye icon) sits next to the 3D Model and
     Drawing fields in the Customer & Part group. Click to open the
     same modal preview as the smart button. Two paths to the same
     content — power users grab the field-adjacent link mid-edit;
     visual-thinkers grab the smart button up top.

Layout collapses to a single full-width column. The .o_fp_cfg_layout
wrapper is kept (display:block) so we have a stable hook in case a
side panel returns later for a different purpose. Old SCSS dance with
:has() selectors to fake-collapse the grid is gone.

Bumped fusion_plating_configurator to 19.0.3.0.0.

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

fusion_plating/fusion_plating_configurator/__manifest__.py

@@ -5,7 +5,7 @@
 
 {
     'name': 'Fusion Plating — Configurator',
-    'version': '19.0.2.0.0',
+    'version': '19.0.3.0.0',
     'category': 'Manufacturing/Plating',
     'summary': 'Quotation configurator with part catalog, coating configs, and formula-based pricing engine.',
     'description': """