fix(config): complete layered home config migration

[christso]

Summary

Layered config is now consistently based on $AGENTV_HOME/config.yaml: Dashboard deployment seeds the new projects: registry shape, global validation no longer mistakes the real home config for a project-local config, and projects[].results is validated with the same result-repo rules as top-level results.

Project-scoped remote status now prefers registered project result settings over global fallback settings, so Dashboard deployments can keep per-project result repos in the home registry without results_by_project.

Verification

• bun test packages/core/test/evaluation/validation/config-validator.test.ts
• bun test packages/core/test/projects.test.ts apps/cli/test/commands/results/serve.test.ts
• bun run build
• bun run typecheck
• bun run lint
• bash -n scripts/setup-dashboard-deployment.sh
• Scratch smoke: agentv validate accepts $AGENTV_HOME/config.yaml with projects: and no false project-local warning.
• Scratch smoke: agentv validate <project>/.agentv/config.yaml warns that projects: is only valid in $AGENTV_HOME/config.yaml.
• Scratch smoke: project-scoped /api/projects/:id/remote/status returns the registered projects[].results repo/path over the global fallback.
• Scratch deployment smoke: scripts/setup-dashboard-deployment.sh --no-start writes home/config.yaml, does not write home/projects.yaml, and preserves unrelated home config keys plus other project entries.

---