Add --python 3.12 flag to all uv tool install/upgrade openhands commands (#151)

This ensures users install OpenHands with Python 3.12, preventing the
version 0.0.0 installation issue that occurs when using unsupported
Python versions.

Updated files:
- openhands/usage/run-openhands/cli-mode.mdx
- openhands/usage/run-openhands/gui-mode.mdx
- openhands/usage/run-openhands/local-setup.mdx
- openhands/usage/windows-without-wsl.mdx

All instances of 'uv tool install openhands' and 'uv tool upgrade openhands'
now include the '--python 3.12' flag.

Co-authored-by: openhands <openhands@all-hands.dev>

Author: xingyaoww

openhands/usage/run-openhands/cli-mode.mdx

@@ -30,7 +30,7 @@ configuration format has changed.
 
     **Install OpenHands:**
     ```bash
-    uv tool install openhands
+    uv tool install openhands --python 3.12
     ```
 
     **Run OpenHands:**
@@ -40,7 +40,7 @@ configuration format has changed.
 
     **Upgrade OpenHands:**
     ```bash
-    uv tool upgrade openhands
+    uv tool upgrade openhands --python 3.12
     ```
   </Tab>
   <Tab title="Executable Binary">
@@ -97,7 +97,7 @@ configuration format has changed.
         --add-host host.docker.internal:host-gateway \
         --name openhands-cli-$(date +%Y%m%d%H%M%S) \
         python:3.12-slim \
-        bash -c "pip install uv && uv tool install openhands && openhands"
+        bash -c "pip install uv && uv tool install openhands --python 3.12 && openhands"
     ```
 
     The `-e SANDBOX_USER_ID=$(id -u)` is passed to the Docker command to ensure the sandbox user matches the host user’s

openhands/usage/run-openhands/gui-mode.mdx

@@ -15,7 +15,7 @@ You can launch the OpenHands GUI server directly from the command line using the
 
 <Info>
 **Prerequisites**: You need to have the [OpenHands CLI installed](/usage/run-openhands/cli-mode) first, OR have `uv`
-installed and run `uv tool install openhands` and `openhands server`. Otherwise, you'll need to use Docker
+installed and run `uv tool install openhands --python 3.12` and `openhands server`. Otherwise, you'll need to use Docker
 directly (see the [Docker section](#using-docker-directly) below).
 </Info>
 

openhands/usage/run-openhands/local-setup.mdx

@@ -78,7 +78,7 @@ See the [uv installation guide](https://docs.astral.sh/uv/getting-started/instal
 
 **Install OpenHands**:
 ```bash
-uv tool install openhands
+uv tool install openhands --python 3.12
 ```
 
 **Launch OpenHands**:
@@ -97,7 +97,7 @@ This will automatically handle Docker requirements checking, image pulling, and
 
 **Upgrade OpenHands**:
 ```bash
-uv tool upgrade openhands
+uv tool upgrade openhands --python 3.12
 ```
 
 <Accordion title="Alternative: Traditional pip installation">

openhands/usage/windows-without-wsl.mdx

@@ -166,7 +166,7 @@ After installation, restart your PowerShell session to ensure the environment va
 After installing the prerequisites, install OpenHands with:
 
 ```powershell
-uv tool install openhands
+uv tool install openhands --python 3.12
 ```
 
 Then run OpenHands:
@@ -178,7 +178,7 @@ openhands
 To upgrade OpenHands in the future:
 
 ```powershell
-uv tool upgrade openhands
+uv tool upgrade openhands --python 3.12
 ```
 
 ### Troubleshooting CLI Issues