fix: explicitly block stored procedure SQL calls

[palakjaiswal16]

Summary

Explicitly blocks stored procedure SQL calls in the read-only query guard so EXEC, EXECUTE, and CALL are rejected intentionally instead of only being blocked incidentally.

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Type of Change

• Bug fix
• New feature
• Refactor (no functional change)
• Documentation update
• UI / style improvement
• Tests
• Config / CI / tooling

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What Was Changed

• Moved isReadOnlySqlQuery into a small query-safety module so it can be tested directly.
• Added exec, execute, and call to the blocked SQL keyword list.
• Added regression tests for read-only queries, hidden writes, and stored procedure calls.

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How to Test

1. Run npm install
2. Run npm test -- --run
3. Run npm run lint

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Checklist

• My code follows the project's TypeScript conventions
• npm run lint passes (no TypeScript errors)
• I have tested my changes locally
• I have added comments where the code is complex or non-obvious
• I have updated relevant documentation (if applicable)
• This PR is linked to an open issue

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Screenshots (if UI change)

Not applicable. This is a backend/query safety change.

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Related Issues / PRs

Closes #74

[Mananwebdev160408]

This PR currently has merge conflicts with the base branch. Please resolve them so we can proceed with merging. Thanks!