fix(plating): CoC signer follows Settings "Certificate Owner" (no stale freeze)

Changing Settings -> Certificate Owner didn't move existing certs: the signer
was snapshotted from the company owner at cert-creation time, and the CoC
prefers that snapshot over the live owner.

- _fp_create_certificates no longer freezes the company owner into
  certified_by_id; it snapshots ONLY a deliberate per-spec signer. Empty
  certified_by_id then resolves the LIVE company owner in the CoC report.
- action_issue lazy-fill made robust: resolves the company via the SO /
  env.company (fp.certificate has no company_id) so it fills the CURRENT
  owner at issue and the "Certified By" gate still passes.
- Settings help text corrected: signature comes from the user's Plating
  Signature (Preferences -> My Profile), not "HR Employee".
- Data fix on entech: cleared certified_by_id on 5 stale draft CoCs with no
  per-spec signer so they follow the current owner.

Bump certificates 19.0.9.3.0, jobs 19.0.11.4.0. Verified: CoC-30058 resolves
signer = Garry Singh (has Plating Signature), renders clean.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

fusion_plating/fusion_plating_certificates/views/res_config_settings_views.xml

@@ -18,7 +18,7 @@
                        help="Branding, accreditation logos, and default signer for Certificates of Conformance.">
                     <setting id="fp_coc_owner"
                              string="Certificate Owner (Default Signer)"
-                             help="Their HR Employee signature appears on issued certificates by default.">
+                             help="Signs every CoC that has no per-spec or per-cert signer. Their Plating Signature (Preferences → My Profile) is printed. Changing this flows through to draft certificates.">
                         <field name="x_fc_owner_user_id"
                                options="{'no_create': True, 'no_open': True}"/>
                     </setting>