Revise README for clarity and structure

[KraitDev]

Description

Updated the README to improve clarity and organization, including a new introduction, features, and usage sections.

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)
• Code Refactor / Performance Improvement

Integration Verification

Because this is published as an npm package, please confirm you have verified your changes against the following:

• Tested via Standalone CLI (npx condense-api or npm start)
• Tested as an Express middleware import (condenseApp)
• Tested programmatically (optimizeImage, optimizeText, or optimizeMediaStream)

Architecture Checklist

• My changes write zero files to local storage (strictly RAM-only).
• No Express dependencies are required inside the src/services logic.
• If dealing with HTML/CSS/JS, the data-condense-ignore / /* condense-ignore */ rules are correctly preserved.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[github-actions]

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