Add agent onboarding documentation for autonomous coding systems

[Copilot]

Overview

Adds AGENT_ONBOARDING.md - a comprehensive technical reference for LLM-based coding agents working on the Redot platform. Document provides complete system context: architecture, tech stack, domain models, execution guidelines, and constraints.

Structure:

• Project Overview - No-code/low-code platform, target users, success criteria
• High-Level Architecture - Turborepo monorepo with 7 apps (landing, admin, builder, blog, cms, redot-apps, brand) and 12 shared packages
• Tech Stack - React 19, Next.js 16, Vite 7, TypeScript 5.8+, TailwindCSS 4, Radix UI, TipTap, pnpm
• Project Structure - Directory tree, naming conventions, dependency rules
• Core Domain Concepts - TypeScript interfaces for RedotApp, AppPage, SiteSetting, StyleInfo, AppPlan with business rules
• Key Features - 8 features with user flows, relevant files, edge cases (visual builder, multi-tenant rendering, CMS, blog, admin)
• Agent Execution Guidelines - Coding standards, file creation rules, testing procedures, command reference
• Known Constraints - Technical limitations (frontend-only repo, build performance), business rules (plan limits), security considerations
• TODO / Future Work - Categorized roadmap (must-have: real-time collaboration, mobile builder; nice-to-have: component library, multilingual; experimental: AI generation)
• Open Questions - TBD items across architecture, backend API, features, technical debt, infrastructure

Example - Data Flow:

User creates RedotApp → POST /api/redot-apps
→ Navigate to Builder → GET /api/redot-apps/{id}
→ Edit page content (auto-save drafts)
→ Publish → POST /api/redot-apps/{id}/publish
→ Visit {subdomain}.redot.app → SSR with @repo/tenant-router + @repo/builder/renderer

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Related Issue

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PR Checklist

• All 10 required sections included with proper structure
• TypeScript interfaces documented for core entities
• Execution guidelines with coding standards and verification steps
• Architectural patterns and constraints explicitly stated
• Code review feedback addressed (TypeScript version consistency, accessibility timeline clarification)

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Additional Information

Document designed for autonomous agent consumption - prioritizes explicitness over brevity. Agents can quickly understand system boundaries (frontend-only), architectural patterns (multi-tenant subdomain routing, Turborepo monorepo), and implementation guidelines (where to place code, how to test, what not to change).

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