Add new-session CLI command and bundled Agentaps skill

[domenkozar]

Local ACP agents can now run agentaps new-session to open and focus an empty session using the calling session's project and agent command. The original session keeps its context and continues running. Each connection gets an authenticated localhost control endpoint, and stale connection requests are rejected.

Bundle a single agentaps skill with new-session as its first command. Include it in local ACP prompts as embedded context when supported, with a text fallback, and filter directly echoed skill blocks from displayed user messages. SSH agents and standalone terminals are not supported.

Validation:

• cargo test --workspace --locked --quiet
• cargo clippy --workspace --locked --all-targets -- -D warnings
• cargo fmt --all -- --check and git diff --check
• Skill validation passed; package contents include the bundled skill and CLI module.