feat: emit cloud events for dependency cooldown and host observations (#243)

* feat: emit cloud events for dependency cooldown and host observations (#237)

Wire cooldown blocks and proxy host observations through the cloud sync
pipeline so they appear as telemetry in Control Tower.

- Cooldown blocks emit PACKAGE_DECISION with COOLDOWN_BLOCKED action and
  PmgDependencyCooldown context (publish date, cooldown days, days since
  publish, days remaining)
- Proxy host observations emit HOST_OBSERVATION with PmgHostObservation
  (hostname, method)
- Session summary now includes cooldown_blocked_count
- Updated buf API dependency for new proto schema

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* format file

* fix: add explicit eventlog mapping for EventTypeDependencyCooldown

Follow the existing pattern where every audit event type has an explicit
case in mapEventType and a corresponding constant in the eventlog package.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Apply suggestion from @devin-ai-integration[bot]

Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Signed-off-by: Abhisek Datta <abhisek.datta@gmail.com>

---------

Signed-off-by: Abhisek Datta <abhisek.datta@gmail.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Abhisek Datta <abhisek.datta@gmail.com>
Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>

internal/eventlog/eventlog.go

@@ -25,6 +25,7 @@ const (
 	EventTypeDependencyResolved    EventType = "dependency_resolved"
 	EventTypeInstallInsecureBypass EventType = "install_insecure_bypass"
 	EventTypeProxyHostObserved     EventType = "proxy_host_observed"
+	EventTypeDependencyCooldown    EventType = "dependency_cooldown"
 	EventTypeSandboxOverride       EventType = "sandbox_override"
 	EventTypeError                 EventType = "error"
 )