docs: Documentation updates for v0.15.4

[askmanu]

Release: 0.15.4

Documentation Plan

• docs/ARCHITECTURE.md
  Update the MCP Integration section to document the timeout configuration for long-running operations. The fix (PR fix #399 Node.js mcp client times out after 60 seconds #400) added resetTimeoutOnProgress: true to the MCP client initialization to prevent premature disconnections during long-running operations. This is important for developers to understand when working with MCP tools that may run for extended periods (e.g., video generation scripts running 2+ minutes).

Additionally, add a note in the Chat System section about Google/Gemini provider compatibility. The fix (Issue #405) added thoughtSignature support in GoogleReader for Gemini 3 Pro Preview models, which require passing the 'thought signature' in functionCall parts (optional in Gemini 2.5 but required in Gemini 3).

• DEVELOPMENT.md
  Add a troubleshooting note in the MCP Tool Servers section about command argument formatting. The fix (Issue [Bug] Regression? Tool command arguments with whitespace get split #404) addresses a regression where tool command arguments containing whitespace were incorrectly split. Developers configuring MCP servers need to understand how to properly format command arguments with spaces - specifically, they should enclose paths containing spaces in double quotes.

This should be added to the existing 'MCP Tool Servers (Optional)' section or as a new subsection under Troubleshooting.

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This issue was automatically generated by askmanu.

[askmanu]

I've created a plan for this release. Let me know if everything looks good and if I can start working on it.