Simplify loaders and improve rollout logs

[arjunkomath]

Summary

• simplify dashboard and server detail loading placeholders to coarse skeleton blocks
• use server names in rollout logs instead of raw server IDs
• remove deployment UUIDs from user-facing rollout log messages

Validation

• pnpm --dir web exec biome check components/dashboard/dashboard-page-skeleton.tsx 'app/(dashboard)/dashboard/servers/[id]/loading.tsx' lib/agent-status.ts lib/inngest/functions/rollout-workflow.ts
• pnpm --dir web exec tsc --noEmit --pretty false
• smart review via local Claude

[github-actions]

React Doctor found no new issues. 🎉

_{Reviewed by React Doctor for commit 7a14476.}