feat(cli): add ACP session creation and listing - #3744

Summary

• Add the Runtime Host seams needed by ACP Session lifecycle work: a bounded single-page Session catalog reader and a one-shot subscription open that never retries on a replacement Host.
• Add an ACP connection-scoped Session registry that creates durable Maka Sessions, continuously consumes one subscription per Session, tracks the latest snapshot, records subscription failures, and cleans up all adapter-owned resources on EOF.
• Implement ACP session/new and cursor-paginated session/list through the official SDK, including canonical cwd filtering, legacy-record omission, stable Runtime Host error mapping, and explicit rejection of unsupported MCP server and additional-directory inputs.
• Extend PR1's transport-only startup contract by owning the deliberately deferred Runtime Host bootstrap: the first implemented Host-backed Session method lazily creates one shared, abortable CLI Host context, while initialize and unsupported methods remain Host-independent.
• Keep session/close unadvertised and returning -32601; durable Runtime Host Sessions are never deleted or archived by adapter cleanup. Active-turn cancellation and adapter-state removal remain follow-up work in PR4 and will be revalidated before that PR starts.

Refs #3132
Builds on #3658 (merged)

PR1 alignment

• Rebased onto main after feat(cli): add ACP stdio server foundation #3658 merged; the PR now contains only the PR2 delta.
• Reuses PR1's official SDK transport and child-process harness rather than introducing a second ACP server path.
• Implements the Runtime Host connection work deliberately deferred by PR1, without weakening PR1's Host-free initialize contract.

Verification

• Focused post-rebase ACP/Host-bootstrap suite — 49 passed, 0 failed, including the official SDK client with a real Runtime Host process.
• npm --workspace maka-agent test — repository total 519 passed, 1 unrelated macOS /private/var versus /var installation-path assertion failed.
• npm --workspace @maka/runtime-host test — 1243 passed, 0 failed, 9 skipped.
• npm run typecheck
• npm run lint
• npm run format:check
• git diff --check
• git range-diff confirms the six PR2 commits were preserved across the rebase; the only manual conflict resolution retained both current main connection-availability notifications and PR2's one-shot subscription open.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex assisted with implementation, tests, rebase/conflict resolution, verification, and review. Every PR2 commit includes a Generated-by: Codex trailer.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No