Add Docker support for home server deployment

Support DATA_DIR env var for configurable CSV directory,
add docker-compose.yml and .dockerignore for containerized hosting.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,6 @@
+.git
+.playwright-mcp
+docs
+pres
+*.png
+test_server.py

docker-compose.yml

@@ -0,0 +1,13 @@
+services:
+  visual-spending:
+    image: node:22-alpine
+    working_dir: /app
+    command: node server.js
+    volumes:
+      - .:/app:ro
+      - ./data:/data
+    environment:
+      - DATA_DIR=/data
+    ports:
+      - "3000:3000"
+    restart: unless-stopped

server.js

@@ -3,6 +3,7 @@ const fs = require('fs');
 const path = require('path');
 
 const PORT = 3000;
+const DATA_DIR = process.env.DATA_DIR || '.';
 
 const MIME_TYPES = {
     '.html': 'text/html',
@@ -15,7 +16,7 @@ const MIME_TYPES = {
 const server = http.createServer((req, res) => {
     // API endpoint to list available months
     if (req.url === '/api/months') {
-        fs.readdir('.', (err, files) => {
+        fs.readdir(DATA_DIR, (err, files) => {
             if (err) {
                 res.writeHead(500, { 'Content-Type': 'application/json' });
                 res.end(JSON.stringify({ error: 'Failed to read directory' }));
@@ -42,6 +43,8 @@ const server = http.createServer((req, res) => {
     let filePath = '.' + req.url;
     if (filePath === './') {
         filePath = './index.html';
+    } else if (filePath.endsWith('.csv')) {
+        filePath = path.join(DATA_DIR, path.basename(filePath));
     }
 
     const extname = path.extname(filePath);