🌐 Add multi-OpenClaw instance support

[fusion94]

Summary

Add support for collecting and viewing stats from multiple OpenClaw installations inside command-center.

Why

The current OpenClaw integration assumes a single local install. That works for one machine, but it does not answer the real operator question once Atlas is spread across multiple hosts, such as Spark, a VPS, or other boxes.

Key constraint

openclaw status --json alone is not enough for the richer analytics already in the dashboard. Features like token and cost windows depend on transcript usage data, so multi-instance support needs a real collection model per instance, not just a single status poll.

Proposed scope

• define multiple named OpenClaw instances in config
• support per-instance collection of runtime health, sessions, recent runs, logs, and usage analytics
• normalize the data into the existing OpenClaw dashboard schema
• add an instance switcher in the UI
• optionally add a fleet aggregate view after the per-instance view works

Collection options to evaluate

• lightweight remote collector on each host returning normalized JSON
• SSH-based collection for openclaw status, logs, and transcript files
• local-only fallback for single-host setups

Acceptance criteria

• command-center can display more than one OpenClaw instance
• each instance has its own runtime health, sessions, logs, and usage analytics
• the UI makes it obvious which instance is being viewed
• single-instance setups continue to work without a complicated migration