chore(FR-2621): upgrade deprecated Node.js 20 GitHub Actions to v5 (#6840)

Resolves #6838 (FR-2621)

## Summary

Bump pinned action versions in hand-maintained workflow files from v4 (Node.js 20) to v5 (Node.js 24) to silence the deprecation warning emitted by the GitHub Actions runner and prepare for:

- **2026-06-02**: Node.js 24 becomes the default; v4 actions are forced onto Node 24 at runtime.
- **2026-09-16**: Node.js 20 removed from the runner.

Reference: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

## Version bumps

| Action | Before | After |
| --- | --- | --- |
| `actions/checkout` | v4 | v5 |
| `actions/setup-node` | v4 | v5 |
| `actions/upload-artifact` | v4 | v5 |
| `actions/download-artifact` | v4 | v5 |
| `pnpm/action-setup` | v4 | v5 |

## Affected files

- `.github/workflows/package.yml` (source of the `build_web` / `build_mac` / `build_desktop` warning surfaced on [run 24710197346](https://github.com/lablup/backend.ai-webui/actions/runs/24710197346))
- `.github/workflows/jest.yml`
- `.github/workflows/storybook-check.yml`
- `.github/workflows/publish-backend.ai-ui.yml`
- `.github/workflows/publish-backend.ai-docs-toolkit.yml`
- `.github/actions/daily-test-improver/coverage-steps/action.yml` (composite action referenced from `daily-test-improver.lock.yml`)

## Out of scope

- `*.lock.yml` agent workflows under `.github/workflows/` are auto-generated from `*.md` specs and already pin v5/v7/v8 by SHA.
- Source `*.md` specs (e.g. `e2e-healer.md`, `e2e-watchdog.md`) and `.github/aw/actions-lock.json` are managed by the gh-aw tooling on a separate cadence; their compiled `*.lock.yml` outputs are already >= v5 by SHA.
- `actions/cache` is already at v5 project-wide.
- Open Dependabot bumps (`#5788`, `#5789`) propose going straight to v6; v5 is chosen here as a conservative stepping stone that already resolves the Node 20 deprecation warning.

## Test plan

- [ ] Trigger `package.yml` via `workflow_dispatch` with `dry_run=true` and confirm no Node.js 20 deprecation warning in `build_web`.
- [ ] Next `jest.yml` run on a PR touching `react/**` or `packages/backend.ai-ui/**` completes without the warning.
- [ ] No behavior changes beyond the action bumps.

> `scripts/verify.sh` intentionally skipped: this PR only touches `.github/workflows/*.yml` and `.github/actions/**/*.yml`, which the harness (Relay / Lint / Format / TypeScript) does not cover.

Author: yomybaby

.github/actions/daily-test-improver/coverage-steps/action.yml

@@ -6,13 +6,13 @@ runs:
   steps:
     # Step 1: Setup Node.js and pnpm
     - name: Install pnpm
-      uses: pnpm/action-setup@v4
+      uses: pnpm/action-setup@v5
       with:
         version: latest
         run_install: false
 
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v5
       with:
         node-version-file: ".nvmrc"
         cache: "pnpm"
@@ -24,7 +24,7 @@ runs:
         echo "Step: Get pnpm store directory" >> coverage-steps.log
 
     - name: Setup pnpm cache
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: ${{ env.STORE_PATH }}
         key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
@@ -146,7 +146,7 @@ runs:
 
     # Step 9: Upload coverage reports as artifacts
     - name: Upload coverage artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v5
       with:
         name: coverage
         path: |

.github/workflows/jest.yml

@@ -21,7 +21,7 @@ jobs:
       react-changed: ${{ steps.changes.outputs.react }}
       backend-ai-ui-changed: ${{ steps.changes.outputs.backend-ai-ui }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: dorny/paths-filter@v3
         id: changes
         with:
@@ -41,15 +41,15 @@ jobs:
       contents: write
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: jwalton/gh-find-current-pr@v1
         id: findPr
-      - uses: pnpm/action-setup@v4
+      - uses: pnpm/action-setup@v5
         name: Install pnpm
         with:
           version: latest
           run_install: false
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v5
         with:
           node-version-file: ".nvmrc"
           cache: "pnpm"
@@ -94,15 +94,15 @@ jobs:
       run:
         working-directory: ./packages/backend.ai-ui
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: jwalton/gh-find-current-pr@v1
         id: findPr
-      - uses: pnpm/action-setup@v4
+      - uses: pnpm/action-setup@v5
         name: Install pnpm
         with:
           version: latest
           run_install: false
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v5
         with:
           node-version-file: ".nvmrc"
           cache: "pnpm"

.github/workflows/package.yml

@@ -36,16 +36,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
-      - uses: pnpm/action-setup@v4
+      - uses: pnpm/action-setup@v5
         name: Install pnpm
         with:
           version: latest
           run_install: false
 
       - name: Install Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v5
         with:
           node-version-file: '.nvmrc'
           cache: 'pnpm'
@@ -67,7 +67,7 @@ jobs:
 
       # Share build artifacts with downstream desktop jobs
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: web-build
           path: |
@@ -91,16 +91,16 @@ jobs:
     environment: ${{ inputs.dry_run != true && 'app-packaging' || 'app-packaging-dryrun' }}
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
-      - uses: pnpm/action-setup@v4
+      - uses: pnpm/action-setup@v5
         name: Install pnpm
         with:
           version: latest
           run_install: false
 
       - name: Install Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v5
         with:
           node-version-file: '.nvmrc'
           cache: 'pnpm'
@@ -109,7 +109,7 @@ jobs:
         run: pnpm install --no-frozen-lockfile
 
       - name: Download web build artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v5
         with:
           name: web-build
 
@@ -159,16 +159,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
-      - uses: pnpm/action-setup@v4
+      - uses: pnpm/action-setup@v5
         name: Install pnpm
         with:
           version: latest
           run_install: false
 
       - name: Install Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v5
         with:
           node-version-file: '.nvmrc'
           cache: 'pnpm'
@@ -177,7 +177,7 @@ jobs:
         run: pnpm install --no-frozen-lockfile
 
       - name: Download web build artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v5
         with:
           name: web-build
 

.github/workflows/publish-backend.ai-docs-toolkit.yml

@@ -17,14 +17,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v4
-      - uses: pnpm/action-setup@v4
+        uses: actions/checkout@v5
+      - uses: pnpm/action-setup@v5
         name: Install pnpm
         with:
           version: latest
           run_install: false
       - name: Install Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v5
         with:
           node-version-file: ".nvmrc"
           cache: "pnpm"

.github/workflows/publish-backend.ai-ui.yml

@@ -17,14 +17,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out Git repository
-        uses: actions/checkout@v4
-      - uses: pnpm/action-setup@v4
+        uses: actions/checkout@v5
+      - uses: pnpm/action-setup@v5
         name: Install pnpm
         with:
           version: latest
           run_install: false
       - name: Install Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v5
         with:
           node-version-file: ".nvmrc"
           cache: "pnpm"

.github/workflows/storybook-check.yml

@@ -18,7 +18,7 @@ jobs:
     # Skip if PR is still in draft
     if: github.event.pull_request.draft == false
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Filter component changes
         id: filter