ci: bump GitHub Actions to Node 24-era versions

actions/checkout v4 -> v5, setup-node v4 -> v5, setup-python v5 -> v6,
upload-artifact v4 -> v5 across all three workflows. Node 20 actions are
deprecated and GitHub forces Node 24 on the runners from 2026-06-16.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: phuryn

.github/workflows/extension-ci.yml

@@ -20,9 +20,9 @@ jobs:
         working-directory: vscode-extension
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v5
         with:
           node-version: "20"
           cache: "npm"
@@ -40,7 +40,7 @@ jobs:
         run: npm run package
 
       - name: Upload .vsix artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: claude-usage-extension-vsix
           path: vscode-extension/*.vsix

.github/workflows/tag-on-merge.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           # Need enough history to diff the whole push range (`before..after`)
           # not just the tip commit. fetch-depth: 0 = full clone; small repo,
@@ -103,7 +103,7 @@ jobs:
 
       - name: Set up Node (to build the .vsix)
         if: steps.detect.outputs.version != ''
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v5
         with:
           node-version: "20"
           cache: "npm"

.github/workflows/tests.yml

@@ -14,10 +14,10 @@ jobs:
         python-version: ["3.9", "3.11", "3.12"]
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
 

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## v1.2.6 — TBD
+
+### Project / docs
+
+- Bumped GitHub Actions to their Node 24-era major versions across all workflows (`actions/checkout@v5`, `actions/setup-node@v5`, `actions/setup-python@v6`, `actions/upload-artifact@v5`), ahead of GitHub forcing Node 24 on the runners (Node 20 actions are deprecated from 2026-06-16).
+
 ## v1.2.5 — 2026-06-15
 
 ### Scanner / CLI