feat(agno): sub-agent event labelling — release 1.0.3.dev0

[GuillaumeSachet]

Summary

Brings feat/subagent-event-labelling onto dev, cut as version 1.0.3.dev0.

Agno drains parallel member runs through a single asyncio.Queue, so two members streaming at once interleave their deltas on the wire. The adapter tracked one text-message slot and one reasoning slot for the whole stream, splicing both speakers into a single bubble under a single name. Both sequences are now tracked per run, and every event a delegated run produces carries AG-UI's subagent_run_id, so a client attributes output by id instead of by matching a display name.

• Surface delegations as SUBAGENT_STARTED / SUBAGENT_FINISHED / SUBAGENT_ERROR
• Forward event metadata through to AG-UI, namespaced under digitalkin
• Label a member's bubble with its author via TEXT_MESSAGE_START.name, replacing the --- name --- header previously injected into the message text
• Close events carry the metadata of whoever opened the sequence, so a consumer filtering on parent_run_id keeps start and end together
• A member's failure emits SUBAGENT_ERROR rather than RUN_ERROR, which AG-UI treats as terminal for the whole stream
• Force-close every open message, reasoning block and delegation before RUN_FINISHED, which AG-UI rejects while any is still active

Pins ag-ui-protocol to the dev build carrying subagent events and event-level metadata; move to >=0.1.21 once that ships stable. Version bumped 1.0.2 -> 1.0.3.dev0 across .bumpversion.toml, pyproject.toml, src/digitalkin/__version__.py and uv.lock.

Test plan

• Pre-commit suite (ruff-check, ruff-format, mypy) passes.
• Full pytest run on the squashed commit: 1512 passed, 10 skipped.