fix(ci): harden issue-branch.yml against Actions injection (sync from Template-Generic)

.mokogit/workflows/issue-branch.yml

@@ -27,14 +27,22 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Create branch and comment
+        # SECURITY: never interpolate github.event.* into a run: script — the
+        # Actions engine splices the raw value into the shell source (command
+        # injection via a crafted issue title). Pass everything through env so
+        # the values arrive as ordinary shell variables that are not re-parsed.
+        env:
+          MOKOGIT_TOKEN: ${{ secrets.MOKOGIT_TOKEN }}
+          REPO: ${{ github.repository }}
+          ISSUE_NUM: ${{ github.event.issue.number }}
+          ISSUE_TITLE: ${{ github.event.issue.title }}
         run: |
-          TOKEN="${{ secrets.MOKOGIT_TOKEN }}"
-          API="${MOKOGIT_URL}/api/v1/repos/${{ github.repository }}"
-          ISSUE_NUM="${{ github.event.issue.number }}"
-          ISSUE_TITLE="${{ github.event.issue.title }}"
+          TOKEN="${MOKOGIT_TOKEN}"
+          API="${MOKOGIT_URL}/api/v1/repos/${REPO}"
 
-          # Build slug from title: lowercase, replace non-alnum with dash, trim
-          SLUG=$(echo "${ISSUE_TITLE}" | tr '[:upper:]' '[:lower:]' | sed 's/[^a-z0-9]/-/g' | sed 's/--*/-/g' | sed 's/^-//;s/-$//' | cut -c1-40)
+          # Build slug from title: lowercase, replace non-alnum with dash, trim.
+          # printf (not echo) so a title beginning with "-" is not read as flags.
+          SLUG=$(printf '%s' "${ISSUE_TITLE}" | tr '[:upper:]' '[:lower:]' | sed 's/[^a-z0-9]/-/g' | sed 's/--*/-/g' | sed 's/^-//;s/-$//' | cut -c1-40)
           BRANCH="feature/${ISSUE_NUM}-${SLUG}"
 
           # Check dev branch exists
@@ -58,7 +66,7 @@ jobs:
             echo "Created branch: ${BRANCH}"
 
             # Comment on issue with branch link
-            REPO_URL="${MOKOGIT_URL}/${{ github.repository }}"
+            REPO_URL="${MOKOGIT_URL}/${REPO}"
             BODY="Branch created: [\`${BRANCH}\`](${REPO_URL}/src/branch/${BRANCH})\n\n\`\`\`bash\ngit fetch origin\ngit checkout ${BRANCH}\n\`\`\`"
 
             curl -sf -X POST \