fix(studio): scope experiment detail pages to project

[christso]

Summary

• keep experiment detail navigation on project-scoped routes in multi-project mode
• reuse a shared experiment detail view for single-project and project-scoped pages
• keep sidebar and breadcrumbs aligned with the selected project context

Red/green UAT

Red

• http://localhost:3118/api/projects/wisetech-academy-evals/runs returned 22 runs
• http://localhost:3118/api/projects/wisetech-academy-evals/experiments reported default:21
• http://localhost:3118/api/runs returned 0 runs
• headless DOM for http://localhost:3118/experiments/default showed No evaluation runs found.

Green

• headless DOM for http://localhost:3119/projects/wisetech-academy-evals/experiments/default no longer showed the empty state
• the same page rendered project-scoped run links like /projects/wisetech-academy-evals/runs/2026-05-19T07-25-33-977Z
• the project experiments tab linked to /projects/wisetech-academy-evals/experiments/default

Validation

• bun run lint
• bun run build
• bun run test

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