feat(quality_dashboard): sixth 'Certificates' tab (Tasks 14-16)

Counts endpoint: certificates block — open=draft, overdue=draft+>24h.
Falls back to {open:0, overdue:0} when fp.certificate isn't installed.

JS: TABS array gains the 6th entry. Existing data-driven OWL template
auto-renders both the header tile and the body panel. Tab opens the
fp.certificate kanban grouped by state, filtered to draft by default.

Deep-link: setup() reads action.context.params.tab. The
cert_awaiting_issuance notification email links to
/odoo/action-fp_quality_dashboard?tab=certificates and lands the QM
on the right tab automatically.

Template: 'Open across all 5' → 'Open across all <tabs.length>' so
it stays correct if more tabs are added later.

Manifest: fusion_plating_quality 19.0.6.6.6 → 19.0.7.0.0
(fusion_plating_certificates already in depends — no change needed).

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

fusion_plating/fusion_plating_quality/static/src/xml/fp_quality_dashboard.xml

@@ -8,7 +8,7 @@
                     <h2 class="mb-2">Quality Overview</h2>
                     <div class="d-flex gap-4">
                         <div>
-                            <div class="o_fp_qd_metric_label">Open across all 5</div>
+                            <div class="o_fp_qd_metric_label">Open across all <t t-esc="tabs.length"/></div>
                             <div class="o_fp_qd_metric_value"><t t-esc="totalOpen"/></div>
                         </div>
                         <div>