feat: setup monorepo using pnpm (#20)

* tests: fix float problems and PAT problem

* extend CONTRIBUTING.md

* extend build documentation, add GH action, fix build on MacOS

* fix build on Vercel

* update .gitignore and CONTRIBUTING.md

* feat: begin work on monorepo

* chore(actions/basic-build): use pnpm

* fix: vercel-deploy

* docs: updates with new folders

* chore: apply PR review comments

---------

Co-authored-by: martin-mfg <2026226+martin-mfg@users.noreply.github.com>

apps/backend/.devcontainer/devcontainer.json

@@ -0,0 +1,33 @@
+{
+    "name": "GitHub Readme Stats Dev",
+    "image": "mcr.microsoft.com/devcontainers/base:ubuntu",
+    "features": {
+        "ghcr.io/devcontainers/features/node:1": { "version": "22" }
+    },
+    "forwardPorts": [3000],
+    "portsAttributes": {
+        "3000": { "label": "HTTP" }
+    },
+    "appPort": [],
+
+    // Use 'postCreateCommand' to run commands after the container is created.
+    "postCreateCommand": "npm install -g vercel",
+
+    // Use 'postStartCommand' to run commands after the container is started.
+    "postStartCommand": "hostname dev && npm install",
+
+    // Configure tool-specific properties.
+    "customizations": {
+        "vscode": {
+            "extensions": [
+                "yzhang.markdown-all-in-one",
+                "esbenp.prettier-vscode",
+                "dbaeumer.vscode-eslint",
+                "github.vscode-github-actions"
+            ]
+        }
+    },
+
+    "remoteUser": "root",
+    "privileged": true
+}