architecture v3: single VM for all agents + Colony

- One e2-standard-4 (4 vCPU, 16GB) instead of one VM per agent
- Agents as isolated Linux users with separate systemd services
- Birth is fast (~30s) — no VM provisioning, just create user + copy files
- Stagger pulse intervals to avoid resource contention
- systemd MemoryMax per agent (4GB cap)
- ~$50/month total instead of $100+

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/colony/src/components/MessageItem.tsx

@@ -96,7 +96,7 @@ export function MessageItem({ message, compact, lastInGroup, replyTarget, onSele
       onClick={() => onSelect(message.id)}
       className={cn(
         "group relative border-l-4 transition-all duration-300 cursor-pointer",
-        compact ? "" : "border-b border-border/50",
+        lastInGroup ? "border-b border-border/50" : "",
         cfg.border,
         selected ? "!border-l-primary bg-primary/5" : isAgent ? "bg-card" : "bg-background",
         "hover:bg-muted/30",