Initial import of the CBDDC codebase with docs and tests. Add a .NET-focused gitignore to keep generated artifacts out of source control.

.github/ISSUE_TEMPLATE/bug_report.md

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+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '...'
+3. Scroll down to '...'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Environment (please complete the following information):**
+ - OS: [e.g. Windows, Ubuntu]
+ - EntglDb Version [e.g. 1.0.0]
+ - .NET Version [e.g. 8.0]
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/feature_request.md

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+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: enhancement
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/pull_request_template.md

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+# Description
+Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context.
+
+Fixes # (issue)
+
+## Type of change
+- [ ] Bug fix (non-breaking change which fixes an issue)
+- [ ] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] Documentation update
+
+## How Has This Been Tested?
+Please describe the tests that you ran to verify your changes.
+
+- [ ] Test A
+- [ ] Test B
+
+## Checklist:
+- [ ] My code follows the style guidelines of this project
+- [ ] I have performed a self-review of my own code
+- [ ] I have commented my code, particularly in hard-to-understand areas
+- [ ] I have made corresponding changes to the documentation
+- [ ] My changes generate no new warnings
+- [ ] I have added tests that prove my fix is effective or that my feature works
+- [ ] New and existing unit tests pass locally with my changes

.github/workflows/ci.yml

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+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: 10.0.x
+
+      - name: Restore
+        run: dotnet restore CBDDC.slnx
+
+      - name: Build (Warnings as Errors)
+        run: dotnet build CBDDC.slnx --no-restore -warnaserror
+
+      - name: Test
+        run: dotnet test CBDDC.slnx --no-build
+
+      - name: Format Check
+        run: dotnet format CBDDC.slnx --verify-no-changes
+
+      - name: Vulnerability Audit
+        shell: bash
+        run: |
+          dotnet package list --project CBDDC.slnx --include-transitive --vulnerable --format json > vuln.json
+          if grep -q '"severity"' vuln.json; then
+            echo "Vulnerable packages detected."
+            cat vuln.json
+            exit 1
+          fi
+
+      - name: Deprecation Audit
+        shell: bash
+        run: |
+          dotnet package list --project CBDDC.slnx --deprecated > deprecated.txt
+          if grep -q "has the following deprecated packages" deprecated.txt; then
+            echo "Deprecated packages detected."
+            cat deprecated.txt
+            exit 1
+          fi