fix(01-03): align Foundry path with pf2e-8.0.3 layout

- Foundry pf2e v8 nests pf2e packs under packs/pf2e/ (v7 had packs/classes/ directly)
- Update FOUNDRY_CLASSES_DIR path to packs/pf2e/classes/
- Document v8 layout in SEED-README and update failure-mode path string
- Pitfall #5 mitigation: comment in seed script explains version-specific path

Worked-example verification (Wizard end-to-end):
- 320 ClassProgression rows seeded (16 classes x 20 levels)
- Wizard L1..L19 carry ARCANE spell-slot increments + L1 has 5 cantrips
- Wizard L1 has choiceType=school, choiceOptionsRef=wizard-school
- 1 ClassFeatureOption row for wizard-school (battle-magic / School of Battle Magic)
- Idempotent on re-run: 0 created, 320 updated, 0 errors

.planning/phases/01-level-up-pf2e-regelkonform/SEED-README.md

@@ -35,9 +35,16 @@ npm run db:seed:class-progression
 Idempotent: running twice does not duplicate rows. Console output reports `created` and
 `updated` counts plus any errors.
 
+## Foundry pf2e v8 layout note
+
+In Foundry pf2e v8 (the pinned tag `pf2e-8.0.3`), class JSONs live under
+`packs/pf2e/classes/`. Earlier major versions (v7) used `packs/classes/` directly. The
+seed script reads from the v8 path; if you bump the pinned tag back to a v7 release,
+update `FOUNDRY_CLASSES_DIR` in `server/prisma/seed-class-progression.ts` accordingly.
+
 ## Failure modes
 
-- **"Foundry pf2e clone not found at server/prisma/data/foundry-pf2e/packs/classes/"** —
+- **"Foundry pf2e clone not found at server/prisma/data/foundry-pf2e/packs/pf2e/classes/"** —
   run the `git clone` step above.
 - **"Class JSON does not match expected schema"** — Foundry pf2e changed the JSON shape
   between major versions. Update the seed parser or pin to an older tag.