Expose factory UID in runner list output

[warp-agent-staging]

Summary

• select each runner's owning Factory UID in the GraphQL query
• include nullable factory_uid in structured runner-list output
• keep the human-readable table unchanged

Validation

• cargo fmt --all -- --check
• CARGO_HOME=/tmp/cargo-home CARGO_BUILD_JOBS=1 cargo check -p warp_graphql
• CARGO_HOME=/tmp/cargo-home CARGO_BUILD_JOBS=1 cargo test -p warp --lib --no-default-features runner_info_serializes_nullable_factory_uid
• CARGO_HOME=/tmp/cargo-home CARGO_BUILD_JOBS=1 cargo build -p warp --bin dev

CLI verification

Built and ran the modified oz-dev CLI against staging. A single --jq query selected one Factory-owned runner and one unassociated runner:

$ oz-dev runner list --output-format json --jq '{factory_owned: ([.[] | select(.factory_uid != null) | {uid, name, factory_uid}] | first), unassociated: ([.[] | select(.factory_uid == null) | {uid, name, factory_uid}] | first)}'
{
  "factory_owned": {
    "uid": "NbSjgkpqaLm2ZcMgmtcbU1",
    "name": "default",
    "factory_uid": "6XVgX5yTzpVUQAOaUE8H4f"
  },
  "unassociated": {
    "uid": "F3HLXihxdUfcD7DnK9JLIr",
    "name": "foreman",
    "factory_uid": null
  }
}

The default text output retains its existing columns (no Factory UID column):

UID                     Name     Description  Shape    OS     Arch    OS Settings                               Scope  Last updated
NbSjgkpqaLm2ZcMgmtcbU1  default               Default  Linux  x86-64  Docker image: warpdotdev/dev-base:latest  Team   12 hours ago

[warp-agent-staging]

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