Recommend fnm for Node.js version management across all platform guides

Author: tjementum

README.md

@@ -66,11 +66,13 @@ For development, you need .NET, Docker, and Node. And GitHub and Azure CLI for s
     winget install Microsoft.DotNet.SDK.10
     winget install Git.Git
     winget install Docker.DockerDesktop
-    winget install OpenJS.NodeJS
+    winget install Schniz.fnm
     winget install Microsoft.AzureCLI
     winget install GitHub.cli
     ```
 
+    We recommend [fnm](https://github.com/Schniz/fnm) which auto-installs the exact Node.js version from [`.node-version`](./application/.node-version) — alternatively use `winget install OpenJS.NodeJS` but it must match the major version in [`.node-version`](./application/.node-version).
+
 </details>
 
 <details>
@@ -82,7 +84,9 @@ Open a terminal and run the following commands (if not installed):
 - Install [Homebrew](https://brew.sh/), a package manager for Mac
 - `brew install --cask dotnet-sdk`
 - `brew install --cask docker`
-- `brew install git node azure-cli gh`
+- `brew install git fnm azure-cli gh`
+
+We recommend [fnm](https://github.com/Schniz/fnm) which auto-installs the exact Node.js version from [`.node-version`](./application/.node-version) — alternatively use `brew install node` instead of `fnm` but it must match the major version in [`.node-version`](./application/.node-version).
 
 </details>
 
@@ -95,7 +99,7 @@ Open a terminal and run the following commands (if not installed):
 1. Install basic tools
 
    ```bash
-   sudo apt update && sudo apt install -y git wget curl
+   sudo apt update && sudo apt install -y git wget curl libnss3-tools
    ```
 
 2. Add Microsoft package repository
@@ -110,29 +114,53 @@ Open a terminal and run the following commands (if not installed):
 3. Install .NET SDK and Docker
 
    ```bash
-   sudo apt-get update
-   sudo apt-get install -y dotnet-sdk-10.0 docker.io docker-compose-v2
+   sudo apt-get update && sudo apt-get install -y dotnet-sdk-10.0 docker.io docker-compose-v2
+   ```
+
+   ```bash
+   sudo systemctl enable --now docker
    sudo usermod -aG docker $USER
-   newgrp docker
    ```
 
-4. Install Node.js (exact version from `.node-version` to avoid lockfile churn). Alternatively, use a Node version manager like [fnm](https://github.com/Schniz/fnm)
+4. Install Node.js via [fnm](https://github.com/Schniz/fnm) (recommended) or directly
+
+   ```bash
+   # Option A: fnm (recommended)
+   curl -fsSL https://fnm.vercel.app/install | bash
+   ```
 
    ```bash
-   NODE_VERSION=$(cat application/.node-version)
-   ARCH=$(dpkg --print-architecture)
-   curl -fsSL https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-$ARCH.tar.xz | sudo tar -xJ -C /usr/local --strip-components=1
+   # Option B: Node.js directly
+   curl -fsSL https://deb.nodesource.com/setup_24.x | sudo -E bash -
+   sudo apt-get install -y nodejs
    ```
 
+   We recommend [fnm](https://github.com/Schniz/fnm) which auto-installs the exact Node.js version from [`.node-version`](./application/.node-version) — if installing Node.js directly it must match the major version in [`.node-version`](./application/.node-version).
+
 5. Trust the HTTPS development certificate
 
    ```bash
    echo 'export SSL_CERT_DIR="$HOME/.aspnet/dev-certs/trust:${SSL_CERT_DIR:-/usr/lib/ssl/certs}"' >> ~/.bashrc
+   ```
+
+   ```bash
    source ~/.bashrc
+   ```
+
+   ```bash
+   dotnet dev-certs https --trust
+   ```
+
+6. **Log out and log back in** to apply Docker group and fnm changes.
+
+7. (Optional) If using Snap Chromium, trust the certificate in its sandbox
+
+   ```bash
+   certutil -d sql:$HOME/snap/chromium/current/.pki/nssdb -L >/dev/null 2>&1 || (mkdir -p $HOME/snap/chromium/current/.pki/nssdb && certutil -d sql:$HOME/snap/chromium/current/.pki/nssdb -N --empty-password)
    dotnet dev-certs https --trust
    ```
 
-6. (Optional) Install GitHub CLI and Azure CLI (needed for CI/CD setup)
+8. (Optional) Install GitHub CLI and Azure CLI (needed for CI/CD setup)
 
    ```bash
    (type -p wget >/dev/null || (sudo apt update && sudo apt-get install wget -y)) \
@@ -148,11 +176,15 @@ Open a terminal and run the following commands (if not installed):
 
 ## 1. Clone the repository
 
+```bash
+git clone https://github.com/platformplatform/PlatformPlatform.git
+```
+
 We recommend you keep the commit history, which serves as a great learning and troubleshooting resource. 😃
 
 ## 2. (Optional) Install the Developer CLI
 
-The PlatformPlatform CLI provides convenient commands for common tasks. Install it globally to use the `pp` command from anywhere in your terminal.
+The PlatformPlatform CLI provides convenient commands for common tasks. From the cloned repository, install it globally to use the `pp` command from anywhere in your terminal.
 
 ```bash
 cd developer-cli