feat(v2/gen): add Kubernetes provider hub (sub-page index)

Audit of fragmentation found only two prefix clusters: aws (fixed in v2.9.34)
and kubernetes. Unlike AWS, kubernetes is well-classified — a rich parent (157
links) with substantial, distinct children (tools 144, networking 64, security
52, monitoring 24, storage 14, autoscaling 13, ...), not 1-3 link stubs. So
NOTHING is merged for kubernetes; this only adds a 'Deep-Dive Topic Pages' hub
to kubernetes.md indexing its 14 substantial sub-pages (Tools · Networking ·
Security · Monitoring · Storage · Autoscaling · Operators · Alternatives ·
Big Data · Tutorials · Backup & Migrations · Client Libraries · Local Dev ·
On-Premise) — purely additive navigation, no merging, no pruning.

Other small pages (pulumi, kustomize, registries, angular, ...) are legitimate
distinct topics, not fragments of a parent, so they are intentionally left
alone. Verified with --render-only; generator-only, CI republishes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/v2_optimizer.py

@@ -97,6 +97,25 @@ class V2VisionEngine:
                 ("aws-backup", "Backup"),
                 ("aws-newfeatures", "New Features"),
             ],
+            # Kubernetes is well-classified (rich parent + substantial distinct
+            # children), so nothing is merged here — the hub is purely an index
+            # so the flagship landing surfaces its deep-dive topic pages.
+            "kubernetes": [
+                ("kubernetes-tools", "Tools"),
+                ("kubernetes-networking", "Networking"),
+                ("kubernetes-security", "Security"),
+                ("kubernetes-monitoring", "Monitoring"),
+                ("kubernetes-storage", "Storage"),
+                ("kubernetes-autoscaling", "Autoscaling"),
+                ("kubernetes-operators-controllers", "Operators"),
+                ("kubernetes-alternatives", "Alternatives"),
+                ("kubernetes-bigdata", "Big Data"),
+                ("kubernetes-tutorials", "Tutorials"),
+                ("kubernetes-backup-migrations", "Backup & Migrations"),
+                ("kubernetes-client-libraries", "Client Libraries"),
+                ("kubernetes-based-devel", "Local Dev"),
+                ("kubernetes-on-premise", "On-Premise"),
+            ],
         }
         
         self.library_criteria = (