deps: bump Go to 1.26.4 across go.mod, Dockerfiles, GH Actions

Workspace-wide sync. luxfi/node already shipped on 1.26.4 in v1.30.6
(commit 121aca1fa9); this is the cross-repo catch-up.

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: ['1.26.3']
+        go-version: ['1.26.4']
 
     steps:
     - name: Checkout code
@@ -68,7 +68,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v5
       with:
-        go-version: '1.26.3'
+        go-version: '1.26.4'
 
     - name: Run Gosec Security Scanner
       uses: securego/gosec@master
@@ -88,7 +88,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        go-version: ['1.26.3']
+        go-version: ['1.26.4']
 
     steps:
     - name: Checkout code

.github/workflows/release.yml

@@ -21,7 +21,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v5
       with:
-        go-version: '1.26.3'
+        go-version: '1.26.4'
 
     - name: Install dependencies
       run: |
@@ -48,7 +48,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v5
       with:
-        go-version: '1.26.3'
+        go-version: '1.26.4'
 
     - name: Build binaries
       run: |