feat(configurator): Part cell rows 2-3 now editable — type to save

Customer feedback: rows 2 (description) and 3 (serials) in the Part
cell rendered as read-only spans. User wanted to edit directly.

New writable computed fields on fp.direct.order.line:
- part_name_editable: compute reads part_catalog_id.name, inverse
  writes back to part.name on the linked catalog record
- serials_text: compute joins serial_ids names with commas; inverse
  parses the typed string and find-or-creates fp.serial records,
  updates the line's serial_ids M2M

Removed the redundant rev separator (display_name already includes
'(Rev X)' so showing it twice was clutter). Rev edits happen by
editing the part record directly via the OPEN button.

OWL widget templates updated:
- Row 2: <input> bound to part_name_editable, t-on-change saves
- Row 3: <input> bound to serials_text, t-on-change parses + saves

SCSS:
- Row 2 input: italic, transparent border, focus tints background yellow
- Row 3 input: small grey text, comma-separated friendly placeholder
- Both disabled-look when no part is picked

Both inputs trigger the inverse method on blur. The G4 sync chain
takes over from there to push line.line_description etc. back to
the part as before — so editing in the line keeps the part defaults
fresh for future orders.

fusion_plating/fusion_plating_configurator/wizard/fp_direct_order_line.py

@@ -478,6 +478,66 @@ class FpDirectOrderLine(models.Model):
         string='Part Name (display)',
         readonly=True,
     )
+    # Writable bridges so the Part cell widget's row-2 description input
+    # and row-3 serials input save back to the underlying records
+    # (part.name and the line's serial_ids M2M) on blur.
+    part_name_editable = fields.Char(
+        string='Part Name (editable)',
+        compute='_compute_part_name_editable',
+        inverse='_inverse_part_name_editable',
+        store=False,
+    )
+    serials_text = fields.Char(
+        string='Serials (text)',
+        compute='_compute_serials_text',
+        inverse='_inverse_serials_text',
+        store=False,
+        help='Comma-separated list of serial numbers — typing here parses, '
+             'creates new fp.serial records as needed, and updates the M2M.',
+    )
+
+    @api.depends('part_catalog_id', 'part_catalog_id.name')
+    def _compute_part_name_editable(self):
+        for rec in self:
+            rec.part_name_editable = rec.part_catalog_id.name or ''
+
+    def _inverse_part_name_editable(self):
+        for rec in self:
+            if rec.part_catalog_id:
+                new_name = (rec.part_name_editable or '').strip()
+                if new_name and new_name != rec.part_catalog_id.name:
+                    rec.part_catalog_id.sudo().write({'name': new_name})
+
+    @api.depends('serial_ids', 'serial_ids.name')
+    def _compute_serials_text(self):
+        for rec in self:
+            rec.serials_text = ', '.join(rec.serial_ids.mapped('name'))
+
+    def _inverse_serials_text(self):
+        Serial = self.env['fp.serial']
+        company_id = self.env.company.id
+        for rec in self:
+            raw = (rec.serials_text or '').strip()
+            if not raw:
+                rec.serial_ids = [(5, 0)]
+                continue
+            names = [n.strip() for n in raw.replace(';', ',').split(',') if n.strip()]
+            if not names:
+                rec.serial_ids = [(5, 0)]
+                continue
+            existing = Serial.search([
+                ('name', 'in', names),
+                ('company_id', '=', company_id),
+            ])
+            existing_by_name = {s.name: s for s in existing}
+            ids = []
+            for name in names:
+                if name in existing_by_name:
+                    ids.append(existing_by_name[name].id)
+                else:
+                    new = Serial.sudo().create({'name': name})
+                    ids.append(new.id)
+            rec.serial_ids = [(6, 0, ids)]
     # Anchor field for the FpExpressActionBtns widget — renders the
     # stacked DWG / OPEN buttons in one list column. The widget reads
     # part_catalog_id from the line; this field's value is unused.