D8: Does Indexarr merge in or stay separate

[thedancingdeveloper]

stackarr-indexer integrates Indexarr today. It overlaps heavily with the Prowlarr-replacement story.

Acceptance: decision recorded; affects P3 indexer work and the Prowlarr façade scope.

[thedancingdeveloper]

🤖 Vogt validation pass — 2026-08-20 (automated review vs dd26a0aa)

Needs maintainer decision — cannot be settled from code. This is decision D8 (§10 open question #5 of docs/UNIFIED-ARR-PLAN.md), which is still listed as an open, unresolved question (unlike D2/D3/D4/D9 which are struck through as resolved). The integration it concerns is still live: crates/stackarr-indexer/src/indexarr.rs and the crates/stackarr-web/src/routes/indexarr.rs route both exist at HEAD. No compat/Prowlarr-façade crate exists yet (no stackarr-compat-*), so the merge-vs-separate scope decision has not been forced by code either way. Valid and pending a product/scope ruling.