feat(configurator): drop legacy description column after dual-field migration (Sub 2 Task 27)

Removes the `description` field from `fp.sale.description.template` now
that all readers (reports, wizard, sale line) consume the new
`internal_description` + `customer_facing_description` pair.

- Model: drop `description = fields.Text(...)` declaration
- Migration 19.0.9.0.0 Step 6: `ALTER TABLE ... DROP COLUMN IF EXISTS description`
- Template form/search views: swap `description` for the two new fields
- Seed data: write new fields instead of legacy column (dupes old text into both)
- Direct-order wizard: remove `tpl.description` fallback in both onchange handlers

Entech column dropped via Odoo's auto-schema-sync during module upgrade
(migration step is for fresh installs).

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

fusion_plating/fusion_plating_configurator/migrations/19.0.9.0.0/post-migration.py

@@ -72,4 +72,13 @@ def migrate(cr, version):
         cr.rowcount,
     )
 
+    # Step 6: Drop legacy description column (all reads migrated to new fields).
+    # Runs after Steps 3 duplicated data into internal_description +
+    # customer_facing_description. Idempotent via IF EXISTS.
+    cr.execute("""
+        ALTER TABLE fp_sale_description_template
+        DROP COLUMN IF EXISTS description
+    """)
+    _logger.info("Sub 2: dropped legacy description column")
+
     _logger.info("Sub 2: migration complete")