Rebrand extension as official StructKit for VS Code and Cursor

[httpdss]

Overview

This PR rebrands the extension from "Struct YAML Support" to the official StructKit extension for VS Code and Cursor, making it ready for publication to the VS Code Marketplace.

Changes

Package Metadata

• Display Name: Changed from "Struct YAML Support" to "StructKit"
• Description: Updated to "Official StructKit extension for VS Code and Cursor with schema validation and intelligent autocomplete"
• Publisher: Kept as kennethbelitzky (unchanged)
• Version: Remains at 0.1.0 for first official release

Configuration Settings Migration

• New Settings: structkit.commandPath and structkit.customStructuresPath
• Old Settings: struct.commandPath and struct.customStructuresPath are now deprecated with warnings
• Default CLI Path: Changed from struct to structkit
• Backward Compatibility: Extension checks both new and old settings, preferring new ones when present

Commands & UI

• Command Category: Changed from "Struct" to "StructKit"
• Status Bar: Updated to show "StructKit" branding
• Error Messages: Updated to reference pip install structkit and correct URLs

Activation Events

• Added explicit activation for .struct.yaml and *.struct.yaml files
• Maintains YAML language activation for broader support

Documentation

• README: Complete rebrand with StructKit terminology
• Installation Instructions: Added clear pip install structkit prerequisite
• Extension Installation: Documented both Marketplace (coming soon) and VSIX install methods
• Configuration Guide: Updated settings references to use structkit.* namespace

Schema

• Updated bundled schema to match official StructKit schema from https://github.com/httpdss/structkit
• Added support for sources property (new in official schema)

Testing

✅ Compilation successful (npm run compile)
✅ Linting passed (npm run lint)
✅ No trailing whitespace
✅ Settings migration logic supports both old and new config keys

Publishing Notes

This PR prepares the extension for publication but does not publish it. To publish:

# Package the extension
npx vsce package

# Publish to marketplace (requires publisher credentials)
npx vsce publish

The extension is now ready for Kenneth to package and publish with his kennethbelitzky publisher account.

Repository

The GitHub repository name (vscode-struct) remains unchanged to preserve the repository URL and history.