feat: update configuration for OpenAI and Anthropic endpoints

- Created a new .env.example file with default environment variables for PORT, OPENAI_UPSTREAM_URL, ANTHROPIC_UPSTREAM_URL, and DATABASE_URL.
- Updated .npmignore to exclude all .env files except .env.example.
- Revised CONTRIBUTING.md to simplify the contribution process and provide clearer setup instructions.
- Enhanced cost.ts with detailed type definitions and improved cost calculation logic.
- Updated proxy.ts to include new environment variables and improved logging functionality.
- Modified README.md to reflect new configuration instructions and usage examples.
- Removed unnecessary dashboard files and streamlined the project structure.

Dockerfile

@@ -1,19 +1,23 @@
 # Dockerfile
 FROM node:22-slim
 
+# Install pnpm
+RUN corepack enable && corepack prepare pnpm@latest --activate
+
 WORKDIR /app
 
 # Copy package files first for caching
-COPY package*.json ./
+COPY package.json pnpm-lock.yaml pnpm-workspace.yaml ./
+COPY dashboard/package.json ./dashboard/
 
 # Install ALL dependencies (including devDeps for TypeScript)
-RUN npm install
+RUN pnpm install --frozen-lockfile
 
 # Copy all source code
 COPY . .
 
 # Compile TypeScript inside container
-RUN npx tsc
+RUN pnpm run build
 
 ENV PORT=8080
 EXPOSE 8080