Migrate user-attachments images to local storage and update exercise-toolkit to v0.8.1 (#357)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: FidelusAleksander <63016446+FidelusAleksander@users.noreply.github.com>

Author: Copilot

.github/images/create-branch-screenshot.png

@@ -18,7 +18,7 @@ Workflows let you automate tasks like building, testing, or deploying your code,
 
 1. In the **Code** tab of your repository, create a new branch named `welcome-workflow`.
 
-   <img width="400" alt="create branch screenshot" src="https://github.com/user-attachments/assets/8aa4a918-c877-4214-9efe-c9a99ca6421b" />
+   <img width="400" alt="create branch screenshot" src="../images/create-branch-screenshot.png" />
 
 1. In the `welcome-workflow` branch, navigate to the `.github/workflows` directory.
 

.github/steps/1-step.md

@@ -16,7 +16,7 @@ env:
 jobs:
   start_exercise:
     name: Start Exercise
-    uses: skills/exercise-toolkit/.github/workflows/start-exercise.yml@v0.7.3
+    uses: skills/exercise-toolkit/.github/workflows/start-exercise.yml@v0.8.1
     with:
       exercise-title: "Hello GitHub Actions"
       intro-message: "Create and run a GitHub Actions workflow."
@@ -31,6 +31,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          ref: main
 
       - name: Get response templates
         uses: actions/checkout@v4