feat(adk): reduction mw support tool_call & tool_resp messages rewrite

[N3kox]

What type of PR is this?

feat

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• This PR title match the format: <type>(optional scope): <description>
• The description of this PR title is user-oriented and clear enough for others to understand.
• Attach the PR updating the user documentation if the current PR requires user awareness at the usage level. User docs repo

(Optional) Translate the PR title into Chinese.

feat(adk/reduction): 新增 ClearRewriteMessagesHandler 功能，支持工具调用 / 工具返回消息消息重写

(Optional) More detailed description for this PR(en: English/zh: Chinese).

en:
This PR adds a new ClearRewriteMessagesHandler to the reduction middleware, allowing users to rewrite assistant and tool message pairs through this preprocessing step before actual tool cleanup.

Since directly removing parameters of certain tool calls (such as write_file/edit_file) may cause hallucination, rewriting them as user messages can both retain the tool call records and remove a large amount of content context.

zh(optional):
本 PR 为 reduction 中间件新增了 ClearRewriteMessagesHandler 功能，允许用户在实际的工具清理前，通过这个预处理环节重写助手和工具消息对。

由于直接移除某些工具调用（如 write_file/edit_file）的参数可能导致幻觉，此时将其重写为 user 消息既可以保留工具调用记录，又可以移除大量的 content 上下文。

(Optional) Which issue(s) this PR fixes:

(optional) The PR that updates user documentation:

[codecov]

Codecov Report

❌ Patch coverage is 92.85714% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.89%. Comparing base (9b80f95) to head (c7ccebc).

Files with missing lines	Patch %	Lines
adk/middlewares/reduction/reduction.go	92.85%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #956      +/-   ##
==========================================
+ Coverage   82.87%   82.89%   +0.01%     
==========================================
  Files         148      148              
  Lines       16740    16788      +48     
==========================================
+ Hits        13874    13916      +42     
- Misses       1904     1911       +7     
+ Partials      962      961       -1     

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[mrh997]

或者返回 error 吧？