feat: add aur support

[BUR4KBEY]

Description

This PR adds a fully automated CI/CD pipeline for maintaining the sidra-bin AUR package.

The AUR integration itself is maintained separately in my dedicated repository: BUR4KBEY/sidra-bin

The goal of this automation is to eliminate manual maintenance by synchronizing the AUR package state with the upstream wimpysworld/sidra release cycle.

Key Changes:

• update.sh: A bash script that queries the GitHub API for the latest wimpysworld/sidra release, updates the PKGBUILD version/checksums, and regenerates .SRCINFO.
• update.yml: A GitHub Action workflow that runs every 6 hours to automatically update and publish the AUR package.
• Enhanced Documentation: Improved README.md documentation with installation instructions and technical details.

Closes #69

Additional Context

This automation was architected through a collaborative effort between the me and AI coding agents (Claude and Gemini).

Technical Highlights:

• Automated Release Tracking: Keeps the AUR package synchronized with upstream Sidra releases.
• AUR Publishing Automation: Automatically commits and pushes updated package files to the AUR repository.

Checklist

• I have performed a self-review of my code
• I have tested my changes and confirmed there are no regressions

[cubic-dev-ai]

No issues found across 1 file

_{Auto-approved: The changes are strictly limited to updating the README with installation instructions for the AUR package, which is a safe, documentation-only update that does not affect any functional code or system logic.}