feat(studio): track unified logs cta variant and auto-dismiss on explore (#46940)

## Summary
The Unified Logs promo banner (shipped in #46847) had two telemetry/UX
gaps I found while auditing the weekly PostHog event review. Its CTA
fired one event for two different user paths with no way to tell them
apart, and clicking "Explore" left the banner in place. This adds an
`is_enabled` property to the CTA event and auto-dismisses the banner on
the Explore path.

## Changes
- Add `is_enabled: boolean` to `unified_logs_banner_cta_button_clicked`.
It is `true` when the user is already enabled and the button navigates
to the logs page ("Explore"), and `false` when not enabled and the
button opens the feature-preview modal ("Enable"). The two cohorts are
now queryable independently, which is what makes the CTA data usable for
measuring adoption.
- Auto-dismiss the banner when an already-enabled user clicks "Explore".
Previously only the X button dismissed it, so an Explore click left the
banner showing on the next project page load. Scoped to the Explore path
on purpose: the not-enabled path only opens a preview modal (it does not
enable), so dismissing there would hide the banner from users who never
enabled.

## Testing
Behavior to verify on the Vercel preview:
- [x] Enabled user clicks "Explore Unified Logs": navigates to the logs
page, banner does not reappear on the next project page load, CTA event
fires with `is_enabled` true.
- [x] Non-enabled user clicks "Enable Unified Logs": preview modal
opens, banner is still present after closing the modal, CTA event fires
with `is_enabled` false.
- [x] X button: banner dismissed as before, dismiss event fires.

Out of scope on purpose: no impression event (it would fire on every
banner render, low-millions of events per month for one banner), so true
click-through rate stays unmeasurable for now.

## Linear
- fixes GROWTH-925


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Improvements**
* Unified Logs banner now intelligently updates behavior based on
feature state.
* When enabled, exploring the feature automatically dismisses the
banner.
  * When disabled, the enable action opens the feature preview flow.
  * Enhanced tracking for banner interactions.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

apps/studio/components/ui/BannerStack/Banners/BannerUnifiedLogs.tsx

@@ -52,7 +52,11 @@ export const BannerUnifiedLogs = () => {
             <Button type="default" size="tiny" asChild>
               <Link
                 href={`/project/${ref}/logs`}
-                onClick={() => track('unified_logs_banner_cta_button_clicked')}
+                onClick={() => {
+                  track('unified_logs_banner_cta_button_clicked', { is_enabled: true })
+                  setIsDismissed(true)
+                  dismissBanner('unified-logs-banner')
+                }}
               >
                 Explore Unified Logs
               </Link>
@@ -62,7 +66,7 @@ export const BannerUnifiedLogs = () => {
               type="default"
               size="tiny"
               onClick={() => {
-                track('unified_logs_banner_cta_button_clicked')
+                track('unified_logs_banner_cta_button_clicked', { is_enabled: false })
                 selectFeaturePreview(LOCAL_STORAGE_KEYS.UI_PREVIEW_UNIFIED_LOGS)
               }}
             >

packages/common/telemetry-constants.ts

@@ -1254,6 +1254,9 @@ export interface MetricsAPIBannerDismissButtonClickedEvent {
  */
 export interface UnifiedLogsBannerCtaButtonClickedEvent {
   action: 'unified_logs_banner_cta_button_clicked'
+  properties: {
+    is_enabled: boolean
+  }
   groups: TelemetryGroups
 }