Improve: install from the Unraid Apps tab with a working icon, free port and restart

[SandObserver]

Summary

• Point the README Unraid section and the landing page installer at the Apps tab; keep the template download as a fallback.
• Use a PNG for the template icon; Unraid saves icons under a .png name, so an SVG icon is blank in the Docker tab.
• Default the template's host port to 8098; 181 Community Applications templates default to 8000.
• Add --restart=unless-stopped to the template; dockerMan sets no restart policy.
• Make the landing page settings panel follow the install method: compose lines, docker run flags, or Unraid field names read from the template at build time.

Testing

Lint, type checks and the full test suite pass; new test checks that template images exist in the repository and the icon is a PNG.

Checklist

• Format, lint, type checks and tests pass.
• DESIGN_VERSION bumped and tests/golden written again if rendered images change.
• CHANGELOG.md updated under Unreleased for user-visible changes.

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