Console plugin: Toolchain management page

[vtz]

Context

Toolchains are a first-class CRD in Bob. Admins need to manage them (create, view build status, check qualification metadata) and developers need to see which toolchains are available for their builds.

Depends on: #44 (scaffold)

Scope

Toolchain List Page

• Navigation item "Toolchains" under the Builds section
• Table: name, image, platform, phase (Ready/Building/Failed), supported boards, age
• Filter by platform / phase

Toolchain Detail Page

• Overview: image, platform, description, supported boards, supported architectures
• Build status: phase, resolved digest, current build run, last build time
• Qualification section (for automotive safety):
  • Tool Impact level (TI1/TI2)
  • Tool Confidence Level (TCL1-4)
  • Qualified ASIL (QM/A/B/C/D)
  • Evidence reference link
• YAML and Events tabs

RBAC Behavior

• Admin perspective: full CRUD on Toolchains
• Developer perspective: read-only list to see what's available