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/rollback.go

@@ -0,0 +1,79 @@
+package dbsync
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+// RollbackLwwOverride 超管按落败快照回滚线上 A 单行。
+// 仅 outcome=applied_source 可回滚：把 loser_payload 写回 remote；无快照则按 pk 删除。
+func RollbackLwwOverride(ctx context.Context, store *FileStore, overrideID string) (*LwwOverride, error) {
+	if store == nil {
+		return nil, fmt.Errorf("store is nil")
+	}
+	o, err := store.GetLwwOverride(overrideID)
+	if err != nil {
+		return nil, err
+	}
+	if o.Outcome != OutcomeApplied {
+		return nil, fmt.Errorf("仅「源端覆盖」记录可回滚（当前 outcome=%s）", o.Outcome)
+	}
+	if strings.TrimSpace(o.ChannelID) == "" {
+		return nil, fmt.Errorf("override missing channel_id")
+	}
+	ch, err := store.GetChannel(o.ChannelID)
+	if err != nil {
+		return nil, fmt.Errorf("channel: %w", err)
+	}
+	table := strings.TrimSpace(o.Table)
+	pkCol := "id"
+	if ch.PKColumns != nil && strings.TrimSpace(ch.PKColumns[table]) != "" {
+		pkCol = ch.PKColumns[table]
+	}
+	db, err := Open(ch.Remote.Driver, ch.Remote.DSN)
+	if err != nil {
+		return nil, fmt.Errorf("open remote: %w", err)
+	}
+	defer db.Close()
+	if err := EnsureMeta(ctx, db, ch.Remote.Driver); err != nil {
+		return nil, err
+	}
+
+	before := SnapshotTargetRow(ctx, db, ch.Remote.Driver, table, pkCol, o.RowPK)
+	ver := time.Now().UnixNano()
+	loser := strings.TrimSpace(o.LoserPayload)
+	op := "upsert"
+	payload := loser
+	if loser == "" || loser == "{}" {
+		op = "delete"
+		payload = fmt.Sprintf(`{%q:%q}`, pkCol, o.RowPK)
+	}
+	if err := ApplyChange(ctx, db, ch.Remote.Driver, table, pkCol, op, payload, ver); err != nil {
+		return nil, fmt.Errorf("apply rollback: %w", err)
+	}
+
+	rec := LwwOverride{
+		ID:            uuid.NewString(),
+		TenantID:      o.TenantID,
+		ChannelID:     o.ChannelID,
+		Table:         o.Table,
+		RowPK:         o.RowPK,
+		Op:            op,
+		Entry:         EntryRollback,
+		Policy:        "manual_rollback",
+		Outcome:       OutcomeRolled,
+		LoserPayload:  before,
+		WinnerPayload: payload,
+		TargetVer:     o.SourceVer,
+		SourceVer:     ver,
+		CreatedAt:     time.Now().UTC(),
+	}
+	if err := store.AddLwwOverride(rec); err != nil {
+		return nil, err
+	}
+	return &rec, nil
+}