feat: real-time deploy log streaming (SSE)

[rdemeritt]

Summary

Deploy log modal currently shows a static snapshot. Logs do not update while a deployment is in progress.

Desired behavior

Logs stream in real-time while a deploy is running — new lines append as Coolify produces them.

Agreed approach — Option A (SSE)

Backend: New endpoint GET /api/sites/:slug/deployments/:id/log-stream

• Uses existing SSE pattern from stats/live (same headers, keep-alive ping)
• Polls Coolify getDeployment() every 1-2s
• Emits only delta (new lines since last emit) to avoid re-sending full log

Frontend: src/routes/sites/[slug]/+page.svelte (log modal, lines ~1862-1894)

• Connect EventSource to the new endpoint when modal opens on a running deploy
• Append incoming lines to display instead of static render
• Close EventSource when deploy reaches terminal state (success / failed)

Files to change

• api/src/routes/sites.ts — add streaming endpoint after line ~1766
• src/routes/sites/[slug]/+page.svelte — wire modal to EventSource

Notes

• Coolify direct log endpoint (/api/v1/applications/{uuid}/logs) is blocked — COOLIFY_API_TOKEN env var is empty in current setup
• Client-side polling (Option B) was considered but rejected — wasteful for long deploys