Add kbu — Kubernetes TUI

[vulcanshen]

Add kbu to API/CLI adaptors section

kbu is a single-pane Kubernetes TUI built
with Go and Bubble Tea. Four keys — Tab / Space / Enter / Esc — drive
the entire tool; Space opens a contextual "what can I do here?" menu on every
panel, so there are no hotkeys to memorize and no setup.

Highlights:

• Relatives navigation — jump between a resource and everything related to
  it (Deployment ⇄ Pods ⇄ ReplicaSet, Ingress ⇄ Service, …)
• Side-by-side YAML compare — diff any two resources
• Embedded persistent shell — a real terminal pane inside the TUI; any
  kubectl / helm workflow you trust rides along
• Helm as a first-class resource — browse releases, values, and history
• Live edit via the Space menu (kubectl edit), log streaming, container exec
• CRD support via dynamic discovery + real-time Watch updates
• Full mouse support (click / double-click drill / right-click menu / wheel)

Note: this project was previously named km8 (v1.7.x and earlier); it was
renamed to kbu as of v2.0.0. The old repository URL redirects.