Add Build Remote Agent phone pairing (gbr/1)

[LinespottingPrivate]

Add Build Remote Agent as a pairing device for this desktop agent.

The paid iOS/Android app spectates (and can inject into) the local session through the free MIT gbr-agent. Protocol gbr/1. Phone is spectator + veto, not orchestrator.

Independent product by Linespotting AB. Not affiliated with xAI or SpaceX.

Pair (unchanged)

curl -fsSL https://grokbuildremote.com/install.sh | bash   # Windows: irm https://grokbuildremote.com/install.ps1 | iex
gbr-agent version          # v0.6.0+
gbr-agent pair             # QR in browser + printed 8-char code
gbr-agent run              # leave running

Phone: open Build Remote Agent → scan the QR or type the 8-char code. Unpair in Settings before changing PCs.

Attach (only these)

How	Where
Bot API	http://127.0.0.1:8788 after gbr-agent run
MCP	stdio gbr-mcp (node mcp/gbr-mcp/bin/gbr-mcp.js)

curl -sS http://127.0.0.1:8788/health
curl -sS http://127.0.0.1:8788/v1/sessions

This PR is docs/example only. No mailbox keys, no X-GBR-Key, no device.json.

[codebuff-team]

This adds documentation for a completely separate third-party commercial product ("Build Remote Agent" by Linespotting AB) into docs/agents-and-tools.md, including install instructions, SHA-256 checksums for external binaries, MCP config pointing at an external repo, and marketing-style copy ("Independent product by Linespotting AB. Not affiliated with xAI or SpaceX.").

This isn't a fix or improvement to Codebuff/Freebuff itself - it's advertising for an unrelated paid app and its companion agent, asking maintainers to host install/pairing docs for a product they don't control, can't vet, and have no way to keep in sync (pinned SHA-256 hashes for a binary release will go stale immediately). There's no indication this integration is sanctioned or was requested by the maintainers, and baking a specific external vendor's product name and URLs into the core docs file is a product-direction change no single contributor should make unilaterally.

If there's a genuine use case for exposing a local Bot API / MCP endpoint for third-party spectator tools, the right path is a generic, vendor-neutral "external integrations" doc section (if one doesn't already exist) that describes the interface Freebuff exposes, not a walkthrough for one company's proprietary app with checksums and repo links.

Recommending close - this reads as vendor placement rather than a docs contribution to this project.