Replace core persona block with configurable text string in codebase

Summary

The core persona block in the system prompt should be replaced with a text string stored in the codebase, making it configurable and easier to maintain.

Current Behavior

The first part of the system prompt (the core persona block) is currently constructed in a way that's not easily customizable.

Proposed Change

• Remove the hardcoded core persona block
• Store the system prompt introduction as a text string in the codebase
• Construct the first part of the system prompt from this configurable text

Benefits

• Maintainability: Easier to update the persona without modifying code logic
• Transparency: The persona text is visible and reviewable in the codebase
• Customizability: Opens the door for users or deployments to customize the core persona
• Testability: The persona text can be tested independently

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Issue created via Claude Code