feat: Full code review, bug fixes, and philosophy book generation

This commit includes:
- A full code review and bug fixes for language drift, package loading, and CLI crashes.
- The generated 15,000-word philosophy manuscript.
- CODE_REVIEW.md and CHANGELOG.md documenting the process.

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
+
+## [Unreleased]
+
+### Fixed
+- **Critical Bug:** Corrected the MiniMax API call in `opus_orchestrator/utils/llm.py`. The `system` prompt is now correctly passed as a top-level field, resolving the issue where the model would ignore instructions and respond in Chinese.
+- **Language Consistency:** Added a universal and explicit instruction to all agent system prompts (`BaseAgent`, `PydanticAI`, `AutoGen`) to respond ONLY in English. This provides multiple layers of defense against language drift.
+- **AutoGen Revision Loop:** Fixed the chapter iteration logic in `opus_orchestrator/autogen_critique.py`. The `Writer` agent is now correctly prompted to revise the chapter text, and the `iterate_chapter` function properly extracts and applies the revised content.
+
+### Added
+- `CODE_REVIEW.md`: A detailed document outlining the findings from the code review, including the root cause analysis of the language drift issue.
+- `CHANGELOG.md`: This file, to track changes to the project.