deps(actions): bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/ci.yml

@@ -37,7 +37,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
@@ -70,7 +70,7 @@ jobs:
     continue-on-error: true  # Don't block CI - some legacy code has type issues
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
@@ -114,7 +114,7 @@ jobs:
           --health-retries 5
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
@@ -193,7 +193,7 @@ jobs:
     needs: [lint, typecheck]
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
@@ -264,7 +264,7 @@ jobs:
           --health-retries 5
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4

.github/workflows/deploy-production.yml

@@ -48,7 +48,7 @@ jobs:
       deploy_tag: ${{ steps.get-sha.outputs.tag }}
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: ${{ inputs.deploy_tag || 'main' }}
           fetch-depth: 0
@@ -109,7 +109,7 @@ jobs:
           --health-retries 5
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: ${{ needs.preflight.outputs.deploy_sha }}
 
@@ -207,7 +207,7 @@ jobs:
     if: always() && (needs.pre-tests.result == 'success' || needs.pre-tests.result == 'skipped') && (needs.backup.result == 'success' || needs.backup.result == 'skipped')
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: ${{ needs.preflight.outputs.deploy_sha }}
 

.github/workflows/deploy-staging.yml

@@ -32,7 +32,7 @@ jobs:
     if: ${{ github.event.inputs.skip_tests != 'true' }}
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
@@ -70,7 +70,7 @@ jobs:
     if: always() && (needs.pre-checks.result == 'success' || needs.pre-checks.result == 'skipped')
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Configure SSH
         run: |

.github/workflows/security.yml

@@ -37,7 +37,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
@@ -78,7 +78,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
@@ -115,7 +115,7 @@ jobs:
     needs: [dependencies]
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4