docs: add autonomous run protocol

[dapi]

What changed

• add a canonical, integration-neutral Autonomous Run Protocol
• define dispatch gates, isolated workspace lifecycle, scheduler state, retry and reconciliation behavior
• define evidence and human handoff requirements
• connect the protocol to Feature Flow and Autonomy Boundaries
• require Feature implementation runs to pass Plan Ready
• require a run-specific session handoff artifact for cross-session continuation

Why

Autonomous delivery runs need a governed contract connecting tracker tasks, canonical delivery artifacts, isolated workspaces, validation evidence, and human review without depending on a specific tracker, agent, CI system, or cloud provider.

The follow-up gate and handoff requirements prevent implementation from starting before the execution plan is ready and preserve run state when work moves between sessions.

Impact

Downstream projects can adapt a single protocol for their runner and integrations while retaining existing routing, lifecycle, validation, and autonomy ownership.

Validation

• memory-bank-cli lint --scope-root template/memory-bank --entrypoint template/memory-bank/README.md
• memory-bank-cli doctor --profile template
• git diff --check
• semantic review against issue acceptance criteria

Closes #69