Add prompt readiness hints for interactive agents

[nikhilachale]

Summary

Adds prompt-readiness handling for interactive agent adapters that receive their initial worker task after the CLI starts.

Why

Some terminal-based agents are not ready to accept input immediately after process launch. AO could send the worker prompt
too early, causing it to be ignored, misparsed, or injected before the interactive prompt was active.

Changes

• Added optional AgentPromptReadinessProvider support for adapters.
• Added PromptReadinessHints with delay, polling, output patterns, timeout, and line count.
• Updated the session manager to wait for readiness before sending PromptDeliveryAfterStart prompts.
• Falls back to sending the prompt after timeout so startup does not block indefinitely.
• Added readiness hints for Cline, Kimi, Kiro, and Crush.
• Adjusted Kiro and Crush worker launches so prompted workers stay interactive and receive prompts after startup.
• Added tests for readiness waits, timeout fallback, and adapter hint coverage.

Verification

GOCACHE=/private/tmp/go-build-ao-agent-readiness go test ./internal/adapters/agent/cline ./internal/adapters/agent/kimi ./
internal/adapters/agent/kiro ./internal/adapters/agent/crush ./internal/session_manager

[nikhilachale]

Fix Copilot worker startup so initial tasks execute immediately.

Previously the Copilot adapter launched copilot interactively and relied on AO to inject the prompt into the
terminal after startup. In practice this could leave the task sitting in the input buffer until the user opened the
worker and pressed Enter.

This changes prompted Copilot launches to use copilot --interactive <prompt>, which keeps the interactive terminal
session alive while automatically submitting the initial task. The adapter now reports PromptDeliveryInCommand, so
the session manager no longer performs post-start prompt injection for Copilot.

Tested:

• GOCACHE=/private/tmp/go-build-ao-copilot go test ./internal/adapters/agent/copilot