fix: pin recyclarr image to major version tag 8 (latest no longer published)

[Canela-san]

What

Pins the Recyclarr image tag from latest to 8 in the compose template.

Why

Recyclarr stopped publishing a latest tag to Docker Hub and GHCR as of v8.6.0, publishing only major version tags like 8 from then on. This makes a fresh arrstack install fail at docker compose pull, since ghcr.io/recyclarr/recyclarr:latest no longer resolves. Fixes #4 .

How it was tested

Confirmed ghcr.io/recyclarr/recyclarr:8 resolves and pulls, then ran a fresh arrstack install on Pop!_OS (Ubuntu based), x64. docker compose pull completed and Recyclarr started normally.

Checklist

• bun test passes
• tsc --noEmit passes (or bun run typecheck)
• No em dashes added (use commas, periods, colons)
• No AI / Claude / Anthropic attribution in commits or prose
• Screenshots attached for TUI changes — not applicable, no TUI change
• Docs updated if behavior or flags changed — not applicable, no behavior or flag change
• New code has tests, or there is a good reason it does not — one line config value change, no new logic to cover