fix(anthropic): fix Anthropic tool call message ordering for Dify compatibility

[QIN2DIM]

Summary

The Anthropic API requires that assistant text content appears before tool_use blocks in the message history, especially when integrating with Dify which stores assistant text and tool calls separately. Previously, text content was appended after tool calls, violating this requirement and potentially causing errors.

This commit refactors the message creation logic to ensure assistant prose is always placed before tool_use content. It introduces a helper method _create_assistant_text_contents to handle both string and structured text content, ensuring correct ordering according to Anthropic's tool-use guidelines.

Change Type

• Documentation / non-plugin change
• Non-LLM plugin (tools, extensions, datasource, etc.)
• LLM plugin

Screenshots / Videos

Before	After

LLM Plugin Checklist

Areas affected by this change (check all that apply)

• Message flow (system messages, user ↔ assistant turn-taking)
• Tool interaction flow (multi-round usage, Agent App and Agent Node)
• Multimodal input (images, PDFs, audio, video, etc.)
• Multimodal output (images, audio, video, etc.)
• Structured output (JSON, XML, etc.)
• Token consumption metrics
• Other LLM functionality (reasoning, grounding, prompt caching, etc.)
• New models / model parameter fixes

Version

• Bumped top-level version in manifest.yaml (not the one under meta)
• dify_plugin>=0.3.0,<0.6.0 is declared in pyproject.toml and locked in uv.lock (or kept in requirements.txt for legacy plugins without uv.lock) — SDK docs

Testing

• Local deployment — Dify version:
• SaaS (cloud.dify.ai)

[gemini-code-assist]

Code Review

This pull request updates the Anthropic LLM implementation to ensure assistant text prose is placed before tool calls, preventing any text from landing between tool_use and tool_result turns. It also introduces a helper method _create_assistant_text_contents to handle both string and list-based message contents. The review feedback suggests using isinstance instead of checking content.type and casting, which simplifies the list comprehension and serves as a cleaner type guard.

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