v0.43.2026040301

Changes:

• #4946: Add githubMcpServer.channel setting for MCP Insiders mode
• #4944: add isSystemInitiated and relevant changes
• #4948: Aligning more terms and UI labels for new codebase index
• #4943: Add a new fetchedValue concept
• #4925: improve ChatSessionCustomizationProvider implementation
• #4942: Move docs/prompts.md to scoped .instructions.md file
• #4941: Make optimized Anthropic prompts the defaults for Claude 4.6
• #4928: update copilot-api and send event_content
• #4939: Sessions - update context keys

This list of changes was auto generated.