v2.5.9

# Changelog

## New Features:

- **Followups:** Added built-in followup suggestions for Agent and Team. See [cookbook](https://github.com/agno-agi/agno/blob/main/cookbook/05_agent_os/followup/followups_agentos.py).
- **Datetime Format:** Added `datetime_format` parameter to Agent and Team, allowing custom `strftime` formatting for datetime context (e.g., ISO-8601, date-only, localized).
- **Tool Hook Message History:** Tool pre/post hooks and agent-level tool_hooks can now access the current run's message history via `run_context.messages`
- **GoogleCalendarTools:** Extended `GoogleCalendarTools` with new tools, service account auth, and cookbooks.

## Bug Fixes:

- **HITL:** Fixed human in the loop to support `add_history_to_context` during multi-round conversations while running
- **Tools:** Removed (None) prefix from tool parameter descriptions
- **Siliconflow Model Provider:** Updated to use correct default `base_url` from `.com` to `.cn`
- **Learning PROPOSE Mode:** Auto-enable chat history for `LearningMode.PROPOSE` for multi-turn confirmation.
- **AgentOS API Docs:** Added descriptions to all `Form/File` parameters across agent, team, and workflow API endpoints for `OpenAPI/Swagger` visibility


## What's Changed
* fix: resolved continue_run, missing history messages issue by @abhi10691 in https://github.com/agno-agi/agno/pull/6888
* fix: remove (None) prefix from tool parameter descriptions by @fehmisener in https://github.com/agno-agi/agno/pull/6906
* feat: add datetime_format to Agent and Team for custom datetime context by @hztBUAA in https://github.com/agno-agi/agno/pull/6649
* feat: expose run message history to tool hooks with mutation safety by @hztBUAA in https://github.com/agno-agi/agno/pull/6652
* feat: built-in followup suggestions for Agent and Team by @ysolanky in https://github.com/agno-agi/agno/pull/6672
* [fix] siliconflow: correct default base_url from .com to .cn by @NIK-TIGER-BILL in https://github.com/agno-agi/agno/pull/6933
* feat: extend GoogleCalendarTools with new tools, service account auth, and cookbooks by @Mustafa-Esoofally in https://github.com/agno-agi/agno/pull/6926
* fix: auto-enable chat history for LearningMode.PROPOSE by @Mustafa-Esoofally in https://github.com/agno-agi/agno/pull/6928
* chore: add form parameter descriptions to AgentOS API endpoints by @uzaxirr in https://github.com/agno-agi/agno/pull/6941
* chore: Release v2.5.9 by @kausmeows in https://github.com/agno-agi/agno/pull/6940

## New Contributors
* @abhi10691 made their first contribution in https://github.com/agno-agi/agno/pull/6888
* @NIK-TIGER-BILL made their first contribution in https://github.com/agno-agi/agno/pull/6933

**Full Changelog**: https://github.com/agno-agi/agno/compare/v2.5.8...v2.5.9