Support constant identifiers in policy name parsing

[Copilot]

The policy generation script (build/lib/policies.ts) previously only supported string literals and localization function calls for policy names, causing failures when developers tried to use constants:

// This would fail policy generation
const CHAT_MCP_POLICY_NAME = 'ChatMCP';

policy: {
    name: CHAT_MCP_POLICY_NAME,  // ParseError: Missing required 'name' property
    minimumVersion: '1.99'
}

Changes Made

Enhanced the StringQ tree-sitter query to support identifier references:

• Added (identifier) @identifier pattern to match constant references
• Implemented resolveIdentifierToString() function to resolve identifiers to their string constant values
• Updated the QType interface and related functions to pass rootNode for identifier resolution
• Maintained full backward compatibility with existing string literals and localization calls

Example Usage

Developers can now define policy names as constants and reference them consistently:

// Policy constants
const CHAT_MCP_POLICY_NAME = 'ChatMCP';

// Use in policy configuration
policy: {
    name: CHAT_MCP_POLICY_NAME,  // ✅ Now works correctly
    minimumVersion: '1.99'
}

This improvement allows policy names to be defined once and reused across multiple locations, reducing the risk of typos and improving maintainability when policy names need to be referenced in multiple places within the codebase.

Fixes #251304.

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