[agno / Gemini] _format_messages merges functionResponse with subsequent user text under stop_after

## Observed symptom [Bug] Gemini._format_messages merges functionResponse with subsequent user text when using stop_after_tool_call=True When using a tool with `@tool(stop_after_tool_call=True)`, the agent run intentionally stops immediately after the tool execution. At this point, the conversation history ends with: 1. `assistant` (`functionCall`) 2. `tool` (`functionResponse`) On the next interaction, when a user sends a new message (`user`), `Gemini._format_messages` maps the previous `tool` message to `role="user"` and naively merges it with the new incoming `user` message into a **single** `Content` object. ## Literal error text ``` **: Fails with ``` ## Environment GitHub issue agno-agi/agno #10455; state=open ## Trigger / context Public GitHub report in agno-agi/agno (FRESH_14D). ## Source evidence - https://github.com/agno-agi/agno/issues/10455 (2026-09-22T14:19:03Z) — evidence_class: PRIMARY_ISSUE_REPORT — GitHub issue #10455 (open) ## Freshness - classification: FRESH_14D - retrieved_at: 2026-10-02T09:40:08.726088Z - scout_id: C1a35f73a09 ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.