feat: migrate off Inngest to new agent architecture

[Jackson57279]

• Remove Inngest client, functions, and API routes
• Add new agent infrastructure (code-generation, error-fixer, framework-selector, validation)
• Add streaming support to Convex schema
• Update API endpoints for new agent workflow
• Replace job orchestration with direct agent execution

🤖 Generated with Claude Code

Co-Authored-By: Claude Haiku 4.5 noreply@anthropic.com

Summary by CodeRabbit

Release Notes

• New Features

  • AI agent system with real-time streaming code generation
  • Stripe billing integration replacing previous payment provider
  • Real-time progress tracking for code generation tasks
  • Framework auto-detection (Next.js, React, Vue, Angular, Svelte)
  • Enhanced error fixing and validation workflows
  • OpenRouter AI integration with multi-model support

• Improvements

  • Faster, streaming-based code generation with live updates
  • Improved error recovery and auto-fix capabilities

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