Add dependabot configuration for automated dependency updates

.github/codeql/codeql-config.yml

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+name: SecureFix CodeQL config
+
+queries:
+  - uses: security-extended
+
+paths-ignore:
+  - "**/bin/**"
+  - "**/obj/**"

.github/dependabot.yml

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+version: 2
+updates:
+  - package-ecosystem: nuget
+    directory: "/src/SecureFix.Api"
+    schedule:
+      interval: weekly
+      day: monday
+    open-pull-requests-limit: 5
+
+  - package-ecosystem: nuget
+    directory: "/src/SecureFix.Core"
+    schedule:
+      interval: weekly
+      day: monday
+    open-pull-requests-limit: 5
+
+  - package-ecosystem: nuget
+    directory: "/tests/SecureFix.Tests"
+    schedule:
+      interval: weekly
+      day: monday
+    open-pull-requests-limit: 5
+
+  - package-ecosystem: docker
+    directory: "/"
+    schedule:
+      interval: weekly
+      day: monday
+    open-pull-requests-limit: 5
+
+  - package-ecosystem: github-actions
+    directory: "/.github/workflows"
+    schedule:
+      interval: weekly
+      day: monday
+    open-pull-requests-limit: 5

.github/workflows/codeql.yml

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+name: CodeQL
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+      - master
+  pull_request:
+    branches:
+      - main
+      - master
+  schedule:
+    - cron: '23 4 * * 1'
+
+permissions:
+  actions: read
+  contents: read
+  security-events: write
+
+jobs:
+  analyze:
+    name: Analyze C#
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v5
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: csharp
+          config-file: ./.github/codeql/codeql-config.yml
+
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@v3
+
+      - name: Perform CodeQL analysis
+        uses: github/codeql-action/analyze@v3
+        with:
+          upload: false