refactor(core): optimize performance, fix concurrency and clean up AGENTS.md design violations

- Concurrency: Added lock protection to WebSocket writes, fixed timer leaks, and prevented config cache listener context leaks.
- Performance: Added memory cache in ObservabilityBufferStore, periodic cleaning in CH Deduplicator, and buffered ZIP batch download writes.
- Design: Introduced Redis caching for OAuth session/tokens, sanitized raw DB error messages, segregated handlers and logics, and standard CAP response envelopes.

internal/apps/edge/runner/wsreconnect.go

@@ -63,8 +63,10 @@ func RunWSReconnectLoop(ctx context.Context, cfg WSReconnectConfig,
 
 // SleepContext pauses execution for the given duration or until the context is canceled.
 func SleepContext(ctx context.Context, d time.Duration) {
+	t := time.NewTimer(d)
+	defer t.Stop()
 	select {
 	case <-ctx.Done():
-	case <-time.After(d):
+	case <-t.C:
 	}
 }