security: harden CI and add CodeQL automation

.github/dependabot.yml

@@ -0,0 +1,19 @@
+version: 2
+updates:
+  - package-ecosystem: nuget
+    directory: /
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 5
+
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 5
+
+  - package-ecosystem: docker
+    directory: /
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 3

.github/workflows/ci.yml

@@ -6,11 +6,10 @@ on:
   pull_request:
     branches: [main]
 
-permissions:
-  contents: read
-
 jobs:
   build-and-test:
+    permissions:
+      contents: read
     runs-on: ubuntu-latest
     timeout-minutes: 15
 
@@ -32,9 +31,14 @@ jobs:
       - name: Test
         run: dotnet test CargoAPI.Tests/CargoAPI.Tests.csproj --configuration Release --no-build --verbosity normal
 
+      - name: Create ephemeral SQL Server password for compose validation
+        shell: bash
+        run: |
+          password="Aa1!$(openssl rand -hex 24)"
+          echo "::add-mask::$password"
+          echo "MSSQL_SA_PASSWORD=$password" >> "$GITHUB_ENV"
+
       - name: Validate Docker Compose configuration
-        env:
-          MSSQL_SA_PASSWORD: CI_Only_Password_2026!
         run: docker compose config --quiet
 
       - name: Build API container image

.github/workflows/codeql.yml

@@ -0,0 +1,40 @@
+name: CodeQL
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    - cron: "29 4 * * 3"
+
+jobs:
+  analyze:
+    name: Analyze C#
+    permissions:
+      contents: read
+      security-events: write
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup .NET 10
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '10.0.x'
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: csharp
+          queries: security-extended
+
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@v3
+
+      - name: Perform CodeQL analysis
+        uses: github/codeql-action/analyze@v3
+        with:
+          category: "/language:csharp"