Tell OpenLoops agents explicit goal context

[andrei-hasna]

Summary

• prepend explicit OpenLoops goal context to agent stdin, including goal id, top objective, current node key/objective, acceptance criteria, prior evidence, and node instruction
• preserve LOOPS_GOAL_* env propagation and add LOOPS_GOAL_NODE_OBJECTIVE for commands/agents
• propagate workflow-level goal context into agent steps, including parent context for nested workflow/step goals
• document Cursor native agent loops and command-loop usage with goal env values
• retain bounded goal evidence in validation/events and configurable Codewith/Codex sandbox support present in the branch

Verification

• bun test src/lib/goal/runner.test.ts src/lib/workflow-runner.test.ts src/lib/agent-adapter.test.ts
• bun run typecheck
• git diff --check
• bun run build
• bun test

Adversarial Review

• Spawned read-only reviewer Meitner. It found two medium issues: Cursor command-loop docs did not include goal context, and nested workflow/step goals dropped parent context. Both were fixed before final verification.