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/api/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "lib": ["ES2022"],
+    "outDir": "dist",
+    "rootDir": "src",
+    "declaration": false,
+    "sourceMap": true
+  },
+  "include": ["src/**/*.ts"]
+}