feat: ship loose-offline dbsync (validate, agent push, LWW audit)

Add UUID/FK channel checks, agent whitelist/push APIs, bindings, super-admin LWW audit with rollback, reconcile rate limits, and sync docs. Default customers stay opt-in; company conflict UI is removed.

Co-authored-by: Cursor <cursoragent@cursor.com>

platform/platform.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+	"time"
 
 	"aijianzhan/platform/internal/config"
 	"aijianzhan/platform/internal/handler"
@@ -39,6 +40,34 @@ func main() {
 	defer cancel()
 	if ctx.DBSync != nil {
 		ctx.DBSync.StartAll(runCtx)
+		ttlDays := c.DBSync.LwwAuditTTLDays
+		if ttlDays <= 0 {
+			ttlDays = 90
+		}
+		go func() {
+			t := time.NewTicker(6 * time.Hour)
+			defer t.Stop()
+			purge := func() {
+				cutoff := time.Now().UTC().Add(-time.Duration(ttlDays) * 24 * time.Hour)
+				n, err := ctx.DBSync.Store().PurgeLwwOverridesBefore(cutoff)
+				if err != nil {
+					fmt.Printf("dbsync lww purge: %v\n", err)
+					return
+				}
+				if n > 0 {
+					fmt.Printf("dbsync lww purge: removed %d\n", n)
+				}
+			}
+			purge()
+			for {
+				select {
+				case <-runCtx.Done():
+					return
+				case <-t.C:
+					purge()
+				}
+			}
+		}()
 	}
 
 	go func() {