Add Skill: SQL Server table reconciliation using Arrow

[kapilsamant]

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• I have read and followed the Guidance for submissions involving paid services.
• My contribution adds a new instruction, prompt, agent, skill, or workflow file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, agent, skill, or workflow with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.
• I am targeting the staged branch for this pull request.

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A Copilot skill for comparing SQL Server tables across two instances to validate data migrations, ETL pipelines, and detect schema drift. It uses the mssql-python driver with Apache Arrow for fast columnar data extraction.
The skill auto-detects primary keys, compares schemas for drift, identifies missing/extra rows and column-level mismatches, and produces a summary report. For large tables (>1M rows), it uses a SHA-256 hash pre-check to minimize data transfer.
The skill collects connection details, generates a single Python reconciliation script, and runs it.

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Type of Contribution

• New instruction file.
• New prompt file.
• New agent file.
• New plugin.
• New skill file.
• New agentic workflow.
• Update to existing instruction, prompt, agent, plugin, skill, or workflow.
• Other (please specify):

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Additional Notes

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By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.

[github-actions]

🔍 Skill Validator Results

⚠️ Warnings or advisories found

Scope	Checked
Skills	1
Agents	1
Total	2
Severity	Count
---	---:
❌ Errors	0
⚠️ Warnings	1
ℹ️ Advisories	0

Summary

Level	Finding
ℹ️	Found 1 skill(s)
ℹ️	[sql-server-table-reconciliation] 📊 sql-server-table-reconciliation: 2,717 BPE tokens [chars/4: 2,789] (standard ~), 18 sections, 3 code blocks
ℹ️	[sql-server-table-reconciliation] ⚠ Skill is 2,717 BPE tokens (chars/4 estimate: 2,789) — approaching "comprehensive" range where gains diminish.
ℹ️	✅ All checks passed (1 skill(s))

Full validator output

```text Found 1 skill(s) [sql-server-table-reconciliation] 📊 sql-server-table-reconciliation: 2,717 BPE tokens [chars/4: 2,789] (standard ~), 18 sections, 3 code blocks [sql-server-table-reconciliation] ⚠ Skill is 2,717 BPE tokens (chars/4 estimate: 2,789) — approaching "comprehensive" range where gains diminish. ✅ All checks passed (1 skill(s)) ```