feat: enable proxy toggle on quick deploy, event log clearing, and UX fixes

- Add enable_proxy toggle to Quick Deploy form (defaults to on)
- Add DELETE /api/events/log/{id} and DELETE /api/events/log endpoints
- Add Clear All button with confirmation on Events page
- Rename "NPM Proxy" to "Enable Proxy" on stage form (provider-agnostic)
- Fix polling interval validation (min 60s) and number input trim errors
- Fix domain field no longer required in settings

web/src/lib/i18n/en.json

@@ -102,6 +102,7 @@
     "tagPatternHelp": "Glob pattern (e.g., dev-*, v*)",
     "maxInstances": "Max Instances",
     "autoDeployLabel": "Auto Deploy",
+    "enableProxy": "Enable Proxy",
     "npmProxy": "NPM Proxy",
     "creating": "Creating...",
     "createStage": "Create Stage",
@@ -658,6 +659,11 @@
     "noEventsDesc": "Events will appear here as they occur.",
     "loadMore": "Load more",
     "newEvents": "new events",
+    "clearAll": "Clear All",
+    "clearAllTitle": "Clear Event Log",
+    "clearAllMessage": "This will permanently delete all event log entries. This cannot be undone.",
+    "cleared": "Cleared {count} events",
+    "clearFailed": "Failed to clear events",
     "filter": {
       "severity": "Severity",
       "source": "Source",