Rewrite README: restructure documentation with architecture, setup, and local development instructions

[syntaxmage05]

Motivation

• Replace the original verbose, HTML-heavy README with a concise, maintainable project overview tailored to Rails+React development.
• Provide clearer developer onboarding steps and a single source of truth for local development, testing, and deployment notes.
• Surface key architecture and tech-stack details so contributors can quickly understand API surface and repo layout.

Description

• Rewrote README.md to remove HTML header/badges and the long feature table and replaced it with structured sections including Overview, Architecture, Tech Stack, API, Repository Layout, Local Development, Testing & Code Quality, Deployment, and Troubleshooting.
• Added concrete setup and run commands such as bundle install, yarn install, bin/rails db:prepare, bin/dev, and docker build -t taskfy:latest . for common workflows.
• Documented backend/frontend responsibilities, API endpoints for resources like /tasks, /users, and /session, and tooling commands for linting and security checks like bin/rubocop and bin/brakeman.
• Included a concise repo layout snippet and notes for port conflicts, dependency fixes, and database reset commands like bin/rails db:drop db:create db:migrate.

Testing

• No automated tests were executed as part of this documentation-only change.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Avoid recommending broken bin/setup bootstrap path

The new README suggests bin/setup as an alternative onboarding flow, but in this repository bin/setup calls system!("bin/yarn") and there is no bin/yarn executable checked in, so fresh contributors following this path will hit a hard setup failure before the app can run. Either remove this recommendation or update it to a command sequence that is actually runnable in the current repo state.

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