docs: move alternative installation methods back to get started and rewrite the overview page

docs/manual/get-started/install-linux-iso.md

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+---
+description: Install Olares on a physical machine using the official ISO image, including system requirements, installation steps, and activation process.
+---
+
+# Install Olares via ISO
+
+This guide explains how to install Olares on a physical machine using the official ISO image.
+
+<!--@include: ./reusables.md{44,51}-->
+
+## Prerequisites
+
+- **Host requirements**:
+  - **CPU**: 4 cores or more.
+  - **Memory**: At least 8 GB of available RAM.
+  - **Storage**: Minimum 150 GB SSD.
+  - **Network**: The device must be connected to a wired LAN.
+  ::: warning SSD required
+  The installation will likely fail if an HDD (mechanical hard drive) is used instead of an SSD.
+  :::
+
+- **Other**: A USB flash drive with at least **8 GB** capacity.
+
+## Create a bootable USB drive
+
+1. Download the latest **Olares Installer ISO** on your computer.
+2. Download and install [**Balena Etcher**](https://etcher.balena.io/).
+3. Insert the USB flash drive into your computer.
+4. Launch Etcher and follow these steps:
+   ![Bootable USB](/images/manual/get-started/iso-flash.png#bordered)
+   - **Image**: Select the Olares ISO.
+   - **Target disk**: Select your USB drive.
+   - Click **Flash** to write the installer to the USB drive.
+
+## Boot from USB drive
+
+1. Insert the bootable USB drive into the target machine.
+2. Enter the **BIOS setup** and set **USB Boot** as the first boot option.
+3. Save and restart. The system will automatically boot into the Olares installer interface.
+
+## Install Olares
+
+1. From the Olares installer interface, select **Install Olares to Hard Disk** and press **Enter**.
+2. The installer will display a list of available disks (e.g., `sda 200G HARDDISK`).  
+   Type `/dev/` followed by the disk name (e.g., `/dev/sda`) to select the installation target. The installation typically takes **4–5 minutes**.
+   :::tip Note
+   During installation, you may see prompts related to NVIDIA GPU drivers.  
+   Simply press **Enter** to confirm.
+   :::
+3. Once you see the message below, the installation has completed successfully:
+
+   ```shell
+   Installation completed successfully!
+   ```
+
+You can now remove the USB drive and press **Ctrl + Alt + Del** to restart.
+
+## Verify installation
+
+After rebooting, the system will enter Ubuntu.
+
+1. Log in using the default credentials:
+
+    * **Username**: `olares`
+    * **Password**: `olares`
+
+2. Run the following command to verify the installation:
+
+   ```bash
+   sudo olares-check
+   ```
+
+   If the output shows the following, Olares has been installed successfully:
+
+   ```bash
+   check list ---------
+   check Olaresd: success
+   check Containerd: success
+   ```
+
+<!--@include: ./install-and-activate-olares.md-->
+
+<!--@include: ./log-in-to-olares.md-->
+
+<!--@include: ./reusables.md{38,42}-->