feat: add Docker support and compile shared package to dist

- Add multi-stage Dockerfile for server containerization
- Add .dockerignore to exclude unnecessary files from build context
- Switch shared package from source to compiled CommonJS output (dist/)
- Server dev/build scripts now build shared package first
- Fix deep imports to use @calchat/shared barrel export
- Update CLAUDE.md with Docker and shared package documentation

packages/shared/tsconfig.json

@@ -1,10 +1,10 @@
 {
   "extends": "../../tsconfig.json",
   "compilerOptions": {
-    "composite": true,
     "declaration": true,
-    "declarationMap": true,
-    "module": "ESNext",
+    "outDir": "dist",
+    "rootDir": "src",
+    "module": "CommonJS",
     "target": "ES2020",
     "moduleResolution": "Node",
     "esModuleInterop": true,