v2.50.0

Evidence-Focused Explore and Blocking CI Watcher

dreb now gives its default Explore subagent a concrete evidence-retrieval role and provides a dedicated blocking tool for GitHub CI waits. Primary agents retain ownership of diagnosis, design, planning, synthesis, and final conclusions, while specialized agents remain available for broader role-matched work.

What changed

• Explore assignments are bounded and concrete. Generated guidance, the bundled agent definition, and mach6 workflows now direct Explore toward files, symbols, documentation, call sites, exact snippets, and explicit data-flow traces.
• Synthesis stays with the primary agent. Root-cause diagnosis, ambiguous requirements, architecture and design decisions, implementation recommendations, and planning are no longer routed to default Explore.
• GitHub CI waits are first-class. The new watch_github_ci tool blocks on gh pr checks --watch --fail-fast, supports the current branch or an explicit PR selector, and returns when checks definitively pass or fail.
• Failure handling is explicit. The watcher distinguishes failed checks from common GitHub CLI errors, preserves diagnostics, bounds streamed output, and cleans up child processes on cancellation.
• Workflow and API coverage are complete. wait now redirects CI monitoring to the watcher; CLI, SDK, extension, RPC, Telegram, README, and mach6 documentation are aligned, with regression coverage for registration, exports, prompt guidance, and runtime behavior.

Implemented in PR 426.