Gen 9 SV: Tera Raid seed search / preview tool

[codemonkey85]

Carved out of #333 as explicitly out of scope for PR #880. Filed for future tracking.

What's missing

The Tera Raid editor (`Raid9Dialog`, shipped in #880) lets the user edit the raw fields of a `TeraRaidDetail`: `IsEnabled`, `AreaID`, `LotteryGroup`, `SpawnPointID`, `Seed`, `Content`, `IsClaimedLeaguePoints`. The raid Pokémon (species, IVs, ability, Tera type, star rating, rewards) is not stored in the save — it's derived from the seed at runtime by the game's RNG.

So #333's checklist asked for editing those derived properties, but they're not editable. Two things are possible given a seed:

1. Preview — "what would this seed produce?" — run the existing PKHeX raid-generation routines and show species / IVs / Tera type / rewards inline in the raid editor.
2. Seed search — "I want a 6★ Charizard with Tera-Fire and 6 perfect IVs in slot 12" → search for a seed that produces that.

Why it's deferred

Per the #333 implementation plan, parked under "Out of scope / open exploration":

Raid Pokémon species / stats / Tera type / star / rewards — derived from seed at runtime; PKHeX has no UI. A seed-search tool would be a separate effort (cross-reference encounter DB raid generators).

Also flagged in open question #5:

Do we want a "what would this seed produce?" preview (running `EncounterTera9` against the current seed) inside the raid editor? Useful but doubles the UI complexity. Defer to v2?

Implementation sketch

• Preview path: call `EncounterTera9` / matching PKHeX raid encounter resolver on the current seed → display species / level / Tera / IVs / ability inline below the seed field.
• Search path: UI to specify desired species + IVs + Tera, then iterate seeds (bounded with cancel button — the search hot loops are the same kind we already deal with in Auto-Legality; see project memory `project_batch_legalize_lessons` for WASM cooperation concerns).

References

• #333 — parent Gen 9 features tracker
• feat(gen9): Gen 9 SV/ZA feature parity — Phases 2-5 of #333 #880 — Phase 4 Tera Raid editor (current raw-field implementation)
• PKHeX raid generators in `PKHeX.Core/Legality/Encounters/Generator/EncounterGenerator9.cs`

[claude]

Thanks for filing this as a dedicated tracking issue. The scope is well-defined — preview (seed → derived Pokémon properties) and seed search (desired properties → seed) are two distinct sub-features, and the implementation sketch gives a clear starting point for both.

The WASM hot-loop concern noted for the search path is worth keeping in mind early; the batch legalize lessons around cooperative cancellation will apply directly here.

Tracked for future work.