feat(runtime): support 32-way agent swarm concurrency

[likun666661]

Summary

• raise the explicit agent_swarm max_concurrency ceiling from 5 to 32 while keeping the default at 3
• raise the shared child-run permit pool to 32 so a requested 32-wide swarm can materialize instead of being silently throttled to 5
• lock the schema and real-run boundary together with a regression test that proves the 32nd swarm child starts after a shared permit is released
• update the Agent Swarm contract documentation

Breaking Changes

None. Existing callers that omit max_concurrency continue to use 3.

Database Migrations

None.

Merge Order

Standalone; no dependent PRs.

Related PRs

None.

Test Plan

• npm --workspace @maka/runtime test
• npm --workspace @maka/runtime run typecheck
• npm run lint
• npm run format:check
• git diff --check