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/internal/dbsync/lww_audit_test.go

@@ -0,0 +1,72 @@
+package dbsync
+
+import (
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestLwwOverrideStoreAndPurge(t *testing.T) {
+	dir := t.TempDir()
+	st, err := NewFileStore(filepath.Join(dir, "dbsync"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	old := LwwOverride{
+		TenantID:  1,
+		ChannelID: "ch1",
+		Table:     "orders",
+		RowPK:     "aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee",
+		Entry:     EntryAgentPush,
+		Policy:    string(PolicyLWWSource),
+		Outcome:   OutcomeApplied,
+		CreatedAt: time.Now().UTC().Add(-100 * 24 * time.Hour),
+	}
+	fresh := LwwOverride{
+		TenantID:  1,
+		ChannelID: "ch1",
+		Table:     "orders",
+		RowPK:     "bbbbbbbb-bbbb-cccc-dddd-eeeeeeeeeeee",
+		Entry:     EntryDrain,
+		Policy:    string(PolicyLWWSource),
+		Outcome:   OutcomeApplied,
+		CreatedAt: time.Now().UTC(),
+	}
+	if err := st.AddLwwOverride(old); err != nil {
+		t.Fatal(err)
+	}
+	if err := st.AddLwwOverride(fresh); err != nil {
+		t.Fatal(err)
+	}
+	list, err := st.ListLwwOverrides(1, "ch1", 10)
+	if err != nil || len(list) != 2 {
+		t.Fatalf("list=%d err=%v", len(list), err)
+	}
+	n, err := st.PurgeLwwOverridesBefore(time.Now().UTC().Add(-90 * 24 * time.Hour))
+	if err != nil || n != 1 {
+		t.Fatalf("purge n=%d err=%v", n, err)
+	}
+	list, err = st.ListLwwOverrides(0, "", 10)
+	if err != nil || len(list) != 1 {
+		t.Fatalf("after purge list=%d err=%v", len(list), err)
+	}
+}
+
+func TestCanReconcile(t *testing.T) {
+	ok, _ := CanReconcile(nil, time.Minute)
+	if !ok {
+		t.Fatal("nil channel should allow")
+	}
+	past := time.Now().UTC().Add(-10 * time.Minute)
+	ch := &Channel{LastReconcileAt: &past}
+	ok, _ = CanReconcile(ch, 5*time.Minute)
+	if !ok {
+		t.Fatal("expected allow")
+	}
+	recent := time.Now().UTC()
+	ch.LastReconcileAt = &recent
+	ok, wait := CanReconcile(ch, 5*time.Minute)
+	if ok || wait <= 0 {
+		t.Fatalf("expected deny wait>0 ok=%v wait=%v", ok, wait)
+	}
+}