Add AsyncColonyToolkit for native async via AsyncColonyClient

[ColonistOne]

Summary

Headline async fix — drops the asyncio.to_thread shim and wires crewai-colony up to the real httpx-backed AsyncColonyClient that landed in colony-sdk 1.5.0.

Before: every _arun() was asyncio.to_thread(sync_method, ...), so a crew that fanned out 10 tool calls under asyncio.gather ran them serialised through a thread pool.

After: a crew that fans out 10 tool calls under asyncio.gather actually runs them in parallel on the event loop, sharing one httpx.AsyncClient connection pool.

from crewai_colony import AsyncColonyToolkit

async with AsyncColonyToolkit(api_key="col_...") as toolkit:
    tools = toolkit.get_tools()
    agent = Agent(role="Colony Scout", tools=tools, ...)
    await crew.kickoff_async()

How it works

• New AsyncColonyToolkit sibling class — same surface as ColonyToolkit, constructs AsyncColonyClient, supports async with / await aclose() for connection-pool cleanup.
• Lazy-imports AsyncColonyClient so the sync toolkit keeps working without httpx. Raises a helpful ImportError if you try to construct AsyncColonyToolkit without the [async] extra.
• _async_safe_run now dispatches on asyncio.iscoroutinefunction(func). Async client → native await. Sync client → asyncio.to_thread fallback (so the existing ColonyToolkit still works from async crews). Same exception/format contract either way — no changes needed across the 31 tool classes.
• Two special-cased tools (ColonyMarkNotificationsRead, ColonyRegister) that don't go through _async_safe_run also dispatch on iscoroutinefunction so they share the native-async benefit.
• New crewai-colony[async] optional extra pulls in colony-sdk[async]>=1.5.0 (which is what brings httpx). The default install stays zero-extra.

Test plan

• pytest — 191 passed (170 → 191, +21 new native-async tests)
• pytest --cov — 100% across all 6 source files (__init__, callbacks, cli, crews, toolkit, tools)
• ruff check clean
• ruff format --check clean
• mypy src/ clean

New tests/test_async_native.py exercises the full async stack via httpx.MockTransport (no network):

• Dispatcher behaviour: native await vs to_thread fallback, error formatting on both paths
• AsyncColonyToolkit construction, retry forwarding, get_tools, read_only / include / exclude / callbacks, async context manager
• End-to-end ColonySearchPosts / ColonyGetPost / ColonyGetMe / ColonyMarkNotificationsRead via mocked transport
• Concurrent fan-out via asyncio.gather over 10 calls

tests/test_coverage.py::TestRegisterAsync rewritten to cover all three branches (native async path, async error path, sync fallback when AsyncColonyClient import fails).

This is PR 2 of 4 heading toward v0.6.0. Up next: verify_webhook re-export + tool wrapper.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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