feat(hawkins): add paid-pilot infrastructure

[htsukamoto5]

Turns the Hawkins fidelity build into the proposed 3-block paid-pilot candidate.

Includes:

• central CONFIG for paid-run choices and 3-block/36-round pilot provenance
• Prolific identifiers, dyad IDs, completion-code submission routes, and terminal outcome fields
• DataPipe incremental egress with retry/replay handling and privacy-safe filenames
• bounded lobby with paid no-match exit for lobby timeout, spectator overflow, and pairing timeout
• timeout/silence-based partner-drop abort with survivor payment route
• completion screen with final flush and researcher JSON fallback
• dependency-free Node tests adapted to Hawkins for pipeline, terminal routing, and dropout detection

Supersedes the reusable paid-run infrastructure from the CW&G stack (#14, #16, #17, #18) for the Hawkins-first direction. Those PRs can now be closed as source material once this replacement is in place.

Verification:

• node tests/pipeline.test.mjs
• node tests/exits.test.mjs
• node tests/dropout.test.mjs
• syntax parse of reference-game-hawkins.html trailing script