feat(control): add runtime traffic metrics and node latency probing

[ksong008]

Summary

This PR adds two runtime capabilities to dae control plane:

• runtime traffic metrics with rolling history
• node latency probing support

It also includes a responsiveness fix for runtime traffic updates.

What changed

• add runtime traffic statistics collection in control plane
• keep rolling runtime history instead of unbounded growth
• expose upload / download rate and total traffic related snapshots for runtime consumers
• improve runtime traffic update responsiveness
• add node latency probing support in outbound dialer / control plane
• provide control-plane access to node latency probe results

Runtime traffic metrics

This PR introduces runtime stats tracking for live traffic observation.

Highlights:

• track upload and download activity continuously during runtime
• keep recent history in a bounded rolling window
• support current-rate style snapshots as well as accumulated totals
• avoid unbounded memory growth by trimming old buckets

Node latency probing

This PR adds control-plane support for latency probing of configured nodes.

Highlights:

• add probing logic for outbound nodes
• expose probe results through control-plane snapshot / trigger methods
• provide a foundation for higher-layer consumers such as dae-wing and daed

Fix included

This PR also includes a responsiveness improvement for runtime traffic updates so runtime stats react faster under active traffic.

Why

These changes are intended to support higher-level runtime dashboards and orchestration UIs that need:

• live traffic overview
• bounded recent traffic history
• node latency measurements
• explicit probe triggering and result snapshots

Scope

This PR only adds the runtime/control-plane capability in dae.

Follow-up changes in upper layers are expected separately:

• dae-wing will consume these capabilities and expose them via API
• daed will consume the API for UI presentation

Manual verification

• start dae and confirm runtime traffic stats are updated while traffic is active
• confirm traffic history remains bounded over time
• confirm runtime totals continue accumulating during process lifetime
• trigger node latency probing and confirm results are produced
• verify no obvious regression in normal runtime behavior

Related follow-up

This PR is intended to be consumed by follow-up dae-wing / daed changes for:

• runtime traffic overview
• node latency testing / display

Tested locally.

Manual verification completed:

• verified runtime traffic metrics update while traffic is active
• verified runtime traffic history remains bounded instead of growing unbounded
• verified runtime totals continue accumulating during process lifetime
• verified node latency probing can be triggered successfully
• verified latency probe results are available from the control plane
• verified no obvious regression in basic runtime behavior during manual testing

Please add the tested label if needed.

[ksong008]

Tested locally.

Manual verification completed:

• verified runtime traffic metrics update while traffic is active
• verified runtime traffic history remains bounded instead of growing unbounded
• verified runtime totals continue accumulating during process lifetime
• verified node latency probing can be triggered successfully
• verified latency probe results are available from the control plane
• verified no obvious regression in basic runtime behavior during manual testing

Please add the tested label if needed.

[dae-prow]

🧪 Since the PR has been fully tested, please consider merging it.