[codex] Complete UI reset with SaladUI and shadcn-vue shell

[pcharbon70]

Summary

• Implements the phased UI reset using a LiveView route shell with SaladUI-backed sections and bounded LiveVue islands using shadcn-vue primitives.
• Replaces the legacy operator UI/shell artifacts with route/section shell naming and removes DaisyUI from the active frontend surface.
• Adds contributor guardrails, shell resilience coverage, cleanup checks, and final browser smoke coverage for the reset.
• Stabilizes browser fixtures for setup, dashboard, conversation, repository inventory, settings, and degraded Vue fallback paths.

Validation

• mix frontend.verify
• npm run e2e:test
• mix compile --warnings-as-errors
• git diff --check

Notes: mix frontend.verify still reports the pre-existing npm audit summary and Rollup pure-comment warnings from dependencies, but they are non-failing in the current gate. A cosmetic .github/workflows/ci.yml step-label change was removed from the branch before publishing so the PR does not require workflow OAuth scope for a non-behavioral CI edit.