fix(workflows): add missing checkout steps for gh CLI

All workflows using gh CLI commands need to be in a git repository context.
Added checkout steps to:
- gen-new-plot.yml (create-sub-issues and summary jobs)
- bot-sync-status.yml
- bot-auto-merge.yml (auto-merge job)
- gen-update-plot.yml (early checkout before gh commands)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: MarkusNeusinger

.github/workflows/bot-auto-merge.yml

@@ -22,6 +22,9 @@ jobs:
       issues: write
 
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
       - name: Extract info from branch
         id: extract
         run: |

.github/workflows/bot-sync-status.yml

@@ -18,6 +18,9 @@ jobs:
       pull-requests: read
 
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
       - name: Determine parent issue
         id: parent
         env:

.github/workflows/gen-new-plot.yml

@@ -114,6 +114,9 @@ jobs:
       issues: write
 
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
       - name: React with eyes emoji
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -318,6 +321,9 @@ jobs:
       issues: write
 
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
       - name: Post summary to main issue
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/gen-update-plot.yml

@@ -19,6 +19,9 @@ jobs:
       issues: write
 
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
       - name: Extract spec ID, library, and sub-issue
         id: extract_info
         env: