chore: scaffold pnpm workspace, container, deploy docs

Two-app pnpm workspace for the gashboard (mining dashboard) project:
@gashboard/api (Express 5 + TS) and @gashboard/web (Vue 3 + Vite + TS).
Shared tsconfig.base.json. Multi-stage Dockerfile (node:22.12-alpine,
non-root, healthchecked) and docker-compose.yml ready to deploy as a
Portainer Stack on Umbrel — joins umbrel_main_network so it can reach
the Datum container directly. .env.example documents every var; README
covers the Portainer deploy flow and the security posture.

Note: Dockerfile has a TODO marker to SHA256-pin the base image before
shipping to production.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/vite.config.ts

@@ -0,0 +1,21 @@
+import { defineConfig } from "vite";
+import vue from "@vitejs/plugin-vue";
+
+export default defineConfig({
+  plugins: [vue()],
+  server: {
+    port: 5173,
+    proxy: {
+      "/api": {
+        target: "http://localhost:8080",
+        changeOrigin: true,
+      },
+      "/healthz": "http://localhost:8080",
+    },
+  },
+  build: {
+    outDir: "dist",
+    sourcemap: true,
+    target: "es2022",
+  },
+});