Add PolinRider malware guard workflow

[khushalVekariya]

Task

• Adds .github/workflows/polinrider-guard.yml — a CI workflow that runs on every push and pull request
• Scans tracked files for known PolinRider malware indicators (file paths, string markers, asset payloads)
• Checks font, image, and SVG assets for embedded JS/shell payloads
• Detects suspicious Git propagation behaviour in .sh, .bat, .cmd, and .ps1 scripts
• Fails the build immediately on any match, blocking the merge

[Copilot]

Pull request overview

Adds a GitHub Actions workflow intended to detect known PolinRider malware indicators in tracked files and common asset/script types, failing CI to block merges when indicators are found.

Changes:

• Introduces .github/workflows/polinrider-guard.yml to run on push, pull_request, and manual dispatch.
• Implements bash-based scanning for known PolinRider-related file paths, string markers, and suspicious payload indicators inside fonts/images/SVGs and shell/Windows scripts.

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