feat(skills): add sql-object-impact-analysis skill

[sudhirp25]

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, workflow, or canvas extension 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, workflow, or canvas extension with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.
• I am targeting the main branch for this pull request.

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Description

New Skill: sql-object-impact-analysis

This PR adds the sql-object-impact-analysis skill to trace downstream and upstream dependencies when modifying or dropping database objects (tables, columns, stored procedures, views, triggers) across SQL schema definitions and application code (C#, TypeScript, etc.).

Why is this needed / What is the uplift over vanilla Copilot?

While standard Copilot Chat performs ad-hoc keyword text searches, standard chat responses often:

1. Miss 2nd-tier transitive dependencies (e.g., views built on views, proc-to-proc call chains, database triggers).
2. Fail to distinguish between verified direct references and unverified dynamic SQL.
3. Provide unstructured answers rather than an actionable pre-change safety report.

This skill enforces a structured 5-step dependency audit (SQL Layer -> Application/ORM Layer -> Confidence Classification -> Blast Radius Risk Summary -> Suggested Verification Steps).

Catalog Check

• Does not duplicate sql-optimization (query performance tuning / execution plans).
• Does not duplicate sql-code-review (security/anti-pattern checks).
• Does not duplicate data-breach-blast-radius (PII exposure).

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Type of Contribution

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

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Additional Notes

• Verified that npm start ran cleanly and updated the generated README and marketplace.json entries.

[github-actions]

🔒 PR Risk Scan Results

Scanned 1 changed file(s).

Severity	Count
🔴 High	0
🟠 Medium	0
ℹ️ Info	0

✅ No matching risk patterns were detected in changed files.

This is an automated soft-gate report. Findings indicate review targets and do not block merge by themselves.

[github-actions]

🔍 Vally Lint Results

✅ All checks passed

Scope	Checked
Skills	1
Agents	0
Total	1

Severity	Count
❌ Errors	0
⚠️ Warnings	0
ℹ️ Advisories	0

Summary

Level	Finding
ℹ️	✅ sql-object-impact-analysis (2/2 checks passed)
ℹ️	✓ [spec-compliance] All 1 skill(s) are spec-compliant.
ℹ️	✓ spec-compliance: All spec checks passed.
ℹ️	✓ [valid-refs] All file references across 1 skill(s) are valid.
ℹ️	✓ valid-refs: All file references resolve to existing files within the skill directory.
ℹ️	1 skill(s) linted, 1 passed

Full linter output

### Linting skills/sql-object-impact-analysis
✅ sql-object-impact-analysis (2/2 checks passed)
    ✓ [spec-compliance] All 1 skill(s) are spec-compliant.
        ✓ spec-compliance: All spec checks passed.
    ✓ [valid-refs] All file references across 1 skill(s) are valid.
        ✓ valid-refs: All file references resolve to existing files within the skill directory.

1 skill(s) linted, 1 passed