docs: add ARCHITECTURE.md, Playwright E2E tests, and doc fixes

[ravishan16]

Summary

Adds comprehensive architecture documentation, a Playwright E2E test suite, and fixes several documentation issues.

Changes

New Files

• ARCHITECTURE.md (670 lines) — Full technical architecture guide with Mermaid diagrams covering system overview, frontend/backend architecture, DB schema (ER diagram), data flow, design system (color tokens, glassmorphism, typography, animations), CI/CD pipeline, local development guide, and testing guide

• playwright.config.ts — Playwright config: Chromium, iPhone 14 viewport (390×844), 30s timeout

• e2e/app.spec.ts — 11 E2E tests across 6 groups:

  Group	Tests	Coverage
  Today Page	2	Empty state, bottom nav tabs
  Routine Management	2	Create single & multiple routines
  Completion Flow	1	Toggle checkbox, progress updates
  Dashboard	2	Empty state, stats after completions
  Settings	3	Sections, Google sign-in, footer links
  Navigation	1	Navigate all 4 main pages

Modified Files

• README.md — Fixed banner image (icon-512.png → logo.svg), streamlined Quick Start (Node 20+), expanded Testing section with E2E setup instructions
• DEPLOYMENT.md — Fixed broken local file:/// link → Google's official OAuth docs
• package.json — Added @playwright/test devDep, test:e2e and test:e2e:headed scripts
• .gitignore — Added Playwright artifacts (test-results/, playwright-report/, .playwright-mcp/)

How to Test

# Unit tests
npm run test

# E2E (requires local Worker on :8787 + Vite on :5173)
npm run test:e2e            # headless
npm run test:e2e:headed     # visible browser

Verification

• ✅ 19/19 unit tests pass
• ✅ 11/11 E2E tests pass (headless)
• ✅ 11/11 E2E tests pass (headed / visible browser)
• ✅ tsc clean
• ✅ Production build succeeds

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the project with detailed architecture documentation, a suite of E2E tests, and several documentation improvements. These changes collectively improve the project's maintainability, testability, and provide better guidance for developers and users.

Highlights

• Architecture Documentation: Introduced a comprehensive ARCHITECTURE.md file detailing the system's architecture, design system, CI/CD pipeline, and local development setup.
• Playwright E2E Tests: Added a Playwright E2E test suite covering key app functionalities, ensuring end-to-end reliability.
• Documentation Fixes: Corrected broken links and improved the README.md and DEPLOYMENT.md files for better user guidance.

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Changelog

• .gitignore
  • Added Playwright artifacts (test-results/, playwright-report/, .playwright-mcp/) to the ignore list.
• ARCHITECTURE.md
  • Added a comprehensive architecture guide with diagrams and details on the system overview, frontend/backend architecture, database schema, data flow, design system, CI/CD, local development, and testing.
• DEPLOYMENT.md
  • Fixed a broken local file link to Google's official OAuth documentation.
• README.md
  • Updated banner image, streamlined Quick Start instructions, and expanded the Testing section with E2E setup instructions.
• e2e/app.spec.ts
  • Implemented E2E tests covering Today Page, Routine Management, Completion Flow, Dashboard, Settings, and Navigation.
• package.json
  • Added @playwright/test as a dev dependency and included test:e2e and test:e2e:headed scripts.
• playwright.config.ts
  • Added Playwright configuration file for E2E testing, specifying Chromium browser, iPhone 14 viewport, and timeout settings.

Activity

• 19/19 unit tests pass
• 11/11 E2E tests pass (headless)
• 11/11 E2E tests pass (headed / visible browser)
• tsc clean
• Production build succeeds

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[gemini-code-assist]

Code Review

This pull request is a fantastic addition to the project, introducing comprehensive architecture documentation and a solid foundation for E2E testing with Playwright. The new ARCHITECTURE.md is exceptionally detailed and will be a great resource for current and future contributors. The documentation fixes and updates to the README.md also significantly improve the developer experience. I have one minor suggestion to fix a rendering issue in the README.md.

[gemini-code-assist]

The emoji for the "Architecture" section heading is not rendering correctly and appears as a replacement character (``). Please replace it with a suitable emoji like 🏛️ or `🏗️` to improve the document's readability.

Suggested change

	## � Architecture
	## 🏛️ Architecture