Cloud mode: support remote BM Cloud projects via API key auth

[bm-clawd]

Context

With PR #555 on basic-memory adding per-project local/cloud routing with API key auth, the plugin should support connecting to BM Cloud projects — not just local ones.

What this enables

• Agent memory stored in the cloud (always-on, accessible from any machine)
• Multiple agents sharing a cloud project (team brain)
• Agents on different machines reading/writing the same knowledge graph
• Humans browsing agent memory in the cloud app or Obsidian

Implementation

• Add cloud config option (boolean or URL)
• Add apiKey config option for BM Cloud authentication
• Pass --cloud or routing flags to bm CLI commands instead of --local
• Respect the per-project routing config from basic-memory's new feature

Config example

{
  "basic-memory": {
    "config": {
      "mode": "both",
      "project": "claw",
      "cloud": true,
      "apiKey": "bm_key_xxx"
    }
  }
}

Depends on

• basic-memory PR #555 (per-project local/cloud routing)