fix: resolve Docker build failures by copying tsconfig.build.json

- Updated Dockerfile to copy all tsconfig*.json files (includes tsconfig.build.json)
- Updated Dockerfile.railway with same fix
- Changed standard Dockerfile to use 'tsc -p tsconfig.build.json' for consistency
- This fixes the missing file errors preventing Docker builds in CI

The issue was that tsconfig.build.json was added for the testing infrastructure
but the Docker COPY commands were not updated to include it.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Dockerfile.railway

@@ -9,8 +9,8 @@ WORKDIR /app
 RUN apk add --no-cache python3 make g++ && \
     rm -rf /var/cache/apk/*
 
-# Copy package files and tsconfig
-COPY package*.json tsconfig.json ./
+# Copy package files and tsconfig files
+COPY package*.json tsconfig*.json ./
 
 # Install all dependencies (including devDependencies for build)
 RUN npm ci --no-audit --no-fund