feat: add Claude/Anthropic AI provider support

[noctuum]

Summary

This PR adds support for Claude (Anthropic) as an AI provider with flexible authentication options.

Features

Dual Authentication Modes

• CLI Mode (default): Uses the installed claude CLI command, authenticated via claude setup-token

  • Perfect for users with Claude Pro/Max subscriptions
  • No API key required
  • Leverages existing Claude Code authentication

• API Mode: Direct API access using Anthropic API key

  • For users with pay-as-you-go API access
  • Simply configure the API key in settings

Configuration

• Automatic mode detection based on API key presence
• Configurable model selection (default: claude-sonnet-4-5-20250929)
• Adjustable temperature setting (0-1)
• Graceful error handling with helpful messages

Changes

• ✨ Add src/claude-utils.ts with Claude API/CLI integration
• 🔧 Update src/config.ts with Claude configuration keys
• 🔌 Update src/generate-commit-msg.ts to support Claude provider
• 📦 Update package.json with Claude settings and @anthropic-ai/sdk dependency
• 📝 Update keywords and description to include Claude/Anthropic

Testing

Tested both authentication modes:

• ✅ CLI mode with claude setup-token authentication
• ✅ API mode with Anthropic API key

Usage

CLI Mode (No API Key Required)

1. Install Claude Code CLI: https://claude.com/claude-code
2. Authenticate: claude setup-token
3. Set AI Provider to claude in extension settings
4. Leave Claude API Key empty

API Mode

1. Get an API key from https://console.anthropic.com/
2. Set AI Provider to claude
3. Configure Claude API Key in settings

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🤖 Generated with Claude Code