repoPaths never reaches node registration on the native-broker path (11.8.0)

[khaliqgant]

Summary

repoPaths (shipped in 11.8.0 via #1581) never reaches the node registration
when agent-relay node up runs with a native broker — the mode every real
fleet node uses. The result: it is currently impossible for any node to declare
repo keys, so repo-based placement can never match.

Measured on the live fleet: 0 of 1045 nodes carry a single repo: tag or
repoKeys value.

Evidence

Verified against the published 11.8.0 artifacts (not source), CLI and broker
binary both at 11.8.0, on node sf-mini.

The child emits repoPaths into its descriptor:

• dist/cli/lib/node-provider-child.js:104 — adds repoPaths to the descriptor
• dist/cli/lib/node-provider-child.js:253 — parseDescriptorRepoPaths(parsed.repoPaths)

The comment there states: "The parent passes these values directly to its
native broker." It does not. A full survey of the shipped package finds every
repoPaths occurrence:

dist/index.cjs:20433-20435          readRepoKeys()   <- reader only
dist/cli/lib/node-provider-child.js:104,105,253,258  <- child emit + parse

No consumer reads descriptor.repoPaths back to hand it to the broker, and
repo_keys appears only twice — a zod schema (dist/index.cjs:16136) and the
same reader (:20430). There is no writer on the native-broker path.

The working emitter lives in @agent-relay/fleet:

• dist/index.js:201 nodeRegistrationTags() — derives repo:<key> tags
• dist/serve-node.js:61,69 — calls it and sets tags at registration

…but serve-node only runs for SDK-style nodes. With a native broker the Rust
process performs registration and is never told the repo keys.

Reproduction

1. Give a node definition a repoPaths map and serve it via
   agent-relay node up --broker-name <n> --config <def>.
2. Read the node back: agent-relay fleet nodes.
3. Observed: tags: [], repoKeys: None. Capabilities from the same
   definition do register (proving the definition is loaded).

Confirmed with --no-spawn and without it, and after upgrading the broker
binary from 11.7.1 to 11.8.0 (agent-relay-broker 11.8.0).

Impact

Repo-based placement cannot be used by any node. A dispatcher that resolves a
target by repo key finds no eligible node and rejects every assignment.

Suggested fix

On the native-broker path, forward the parsed descriptor.repoPaths (or the
derived nodeRegistrationTags() output) into the broker's registration payload,
which already models repo_keys: Option<Vec<String>>.

Please include a test that asserts a node started with a repoPaths definition
registers with the derived repo:<owner/name> keys, and one asserting a
definition without repoPaths leaves existing tags unchanged.