feat: update environment variables and enhance documentation structure

Author: pphatdev

.env.example

@@ -7,9 +7,9 @@ WARMUP_USERNAME=pphatdev
 # Cloudflare / Wrangler / D1
 # Used by drizzle.config.ts when running Drizzle commands against D1.
 # Keep these empty for local SQLite development.
-# CLOUDFLARE_ACCOUNT_ID=
-# CLOUDFLARE_D1_DATABASE_ID=
-# CLOUDFLARE_API_TOKEN=
+CLOUDFLARE_ACCOUNT_ID=
+CLOUDFLARE_D1_DATABASE_ID=
+CLOUDFLARE_API_TOKEN=
 
 # Redis Cache Configuration (optional)
 # If not set, defaults to redis://localhost:6379

CONTRIBUTING.md

@@ -2,6 +2,12 @@
 
 Thank you for your interest in contributing to GitHub Stats! 🎉
 
+## Getting Started
+
+Before contributing, please review:
+- [Project Structure](docs/PROJECT_STRUCTURE.md) - Understand the codebase organization
+- [Development Guide](docs/how-to/DEVELOPMENT.md) - Setup and development workflow
+
 ## How to Contribute
 
 ### Reporting Bugs
@@ -35,7 +41,7 @@ We welcome feature suggestions! Please create an issue with:
 
 To add a new theme:
 
-1. Edit the appropriate file in `src/utils/themes/`:
+1. Edit the appropriate file in `src/shared/utils/themes/`:
    - `base.ts` - General-purpose themes (stats, languages)
    - `graph.ts` - Graph/heatmap optimized themes
    - `badge.ts` - Badge-specific themes

README.md

@@ -330,9 +330,10 @@ Project visitors increment once per same IP every 5 minutes.
 
 ## Development
 
-Development setup was moved to: [docs/how-to/DEVELOPMENT.md](docs/how-to/DEVELOPMENT.md)
-
-Route-by-route demos with option examples: [docs/example/README.md](docs/example/README.md)
+**Documentation:**
+- [Development Setup Guide](docs/how-to/DEVELOPMENT.md) - Environment setup, database, and run commands
+- [Project Structure](docs/PROJECT_STRUCTURE.md) - Complete codebase architecture and organization
+- [Route Examples](docs/example/README.md) - Route-by-route demos with option examples
 
 ## Architecture