Add Fedora Copr (or hosted DNF repo) for one-line install + auto-update

[IsraelAraujo70]

Today users install via direct RPM URL:

sudo dnf install https://github.com/IsraelAraujo70/prism/releases/latest/download/Prism-X.Y.Z-1.x86_64.rpm

Works, but no auto-update on dnf upgrade.

Options

A. Fedora Copr (recommended)

• Hosted by Fedora Infra; free.
• Builds from a .spec in mock chroots (F40, F41, rawhide).
• User flow: dnf copr enable israelaraujo70/prism && dnf install prism.
• Blockers / unknowns:
  • Tauri build needs Bun (not in Fedora repos) — install via curl -fsSL https://bun.sh/install | bash in %prep, or fall back to npm.
  • Cargo deps need to be vendored (cargo vendor) for offline mock builds.
  • WebKit2GTK 4.1 is in Fedora 40+ — should work without extra flags.

B. GitHub Pages-hosted DNF repo

• CI runs createrepo_c over the released RPMs, pushes metadata to gh-pages branch.
• User flow: sudo dnf config-manager --add-repo https://israelaraujo70.github.io/prism/prism.repo && sudo dnf install prism.
• Pros: simpler than Copr; no third-party dependency.
• Cons: repo metadata signing (GPG) is fiddly without a key infra.

Tasks

• Pick A or B
• If A: register Copr project, write .spec, vendor cargo deps, test build for F40/F41
• If B: enable GH Pages, add createrepo_c step to release workflow, generate prism.repo
• Update README install section
• Smoke test: fresh Fedora KDE VM, run install one-liner, launch app