[BUG] VineyardEngine.CheckRuntimeReady() always returns true without checking actual runtime state

[adityaupasani2]

What's wrong

VineyardEngine.CheckRuntimeReady() in pkg/ddc/vineyard/runtime_info.go is an unimplemented stub:

func (e *VineyardEngine) CheckRuntimeReady() (ready bool) {
    //TODO implement me
    return true
}

This means data operations (DataLoad, DataMigrate, DataProcess) will be dispatched against a VineyardRuntime even when workers are not actually ready, potentially causing failures.

Impact

CheckRuntimeReady() is called in pkg/ddc/base/operation.go before executing data operations. Returning true unconditionally bypasses this gate entirely for VineyardRuntime.

Proposed fix

Implement it using the existing CheckWorkersReady() helper, same as the fix applied to ThinEngine in #6062. Fuse readiness is intentionally excluded because fluid treats fuse as always-ready by design (pkg/ctrl/fuse.go: "fluid assumes fuse components are always ready") — checkFuseHealthy() delegates to CheckAndSyncFuseStatus which unconditionally returns ready = true.

I'd like to work on this.