Rename images/ to shared-images/ and add code scanning screenshots

Rename the shared images folder to better reflect its cross-workshop purpose.
Add screenshots for Dependabot, secret scanning, and code scanning setup.
Remove number prefixes from image filenames.
Update image paths in all workshop setup files.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: GeekTrainer

content/1-hour/0-setup.md

@@ -17,14 +17,14 @@ Let's create the repository you'll use for your workshop.
 1. Navigate to [the repository root](/)
 2. Select **Use this template** > **Create a new repository**
 
-    ![Screenshot of Use this template dropdown](../images/setup-use-template.png)
+    ![Screenshot of Use this template dropdown](../shared-images/setup-use-template.png)
 
 3. Under **Owner**, select the name of your GitHub handle, or the owner specified by your workshop leader.
 4. Under **Repository**, set the name to **pets-workshop**, or the name specified by your workshop leader.
 5. Ensure **Public** is selected for the visibility, or the value indicated by your workshop leader.
 6. Select **Create repository from template**.
 
-    ![Screenshot of configured template creation dialog](../images/setup-configure-repo.png)
+    ![Screenshot of configured template creation dialog](../shared-images/setup-configure-repo.png)
 
 In a few moments a new repository will be created from the template for this workshop!
 

content/full-day/0-setup.md

@@ -12,12 +12,12 @@ Let's create the repository you'll use for your workshop.
 
 1. Navigate to [the repository root][repo-root]
 2. Select **Use this template** > **Create a new repository**
-    ![Screenshot of Use this template dropdown](../images/setup-use-template.png)
+    ![Screenshot of Use this template dropdown](../shared-images/setup-use-template.png)
 3. Under **Owner**, select the name of your GitHub handle, or the owner specified by your workshop leader.
 4. Under **Repository**, set the name to **pets-workshop**, or the name specified by your workshop leader.
 5. Ensure **Public** is selected for the visibility, or the value indicated by your workshop leader.
 6. Select **Create repository from template**.
-    ![Screenshot of configured template creation dialog](../images/setup-configure-repo.png)
+    ![Screenshot of configured template creation dialog](../shared-images/setup-configure-repo.png)
 
 In a few moments a new repository will be created from the template for this workshop!