Bridge scheduler handoff context with memory

[cloga]

Summary

• Build bounded scheduler context packets from task state and recent important task_events.
• Inject inherited scheduler context into scheduler-dispatched Agent Runtime prompts while leaving direct delegate paths unchanged.
• Add scheduler resume context API for master recovery.
• Add explicit scheduler memory promotion, without automatic memory writes from checkpoint/handoff/yield.
• Add regression tests for packet formatting, prompt injection, no automatic memory pollution, MCP schemas, and HTTP contracts.

Fixes #679

Validation

• npm run check-types
• npm run build
• npx vitest run src\test\schedulerContext.test.ts src\test\masterScheduler.test.ts src\test\httpRuntimeHelpers.test.ts src\test\delegate-task-compat.test.ts
• Non-live-smoke Vitest suite: 50 files / 488 tests passed