fix(seed): route prisma db seed through pnpm run for cwd resolution (#234)

## Summary

Follow-up fix on [#233](#233). The `prisma db seed` command failed with `Cannot find module './seed.ts'` because the seed command's path was resolved against the user's cwd (`apps/portal-bff/`) and doubled into `apps/portal-bff/apps/portal-bff/prisma/seed.ts`.

Root cause: Prisma CLI spawns the seed command with cwd = wherever the user invoked `prisma db seed` from. The path `apps/portal-bff/prisma/seed.ts` only works if cwd is the workspace root, but the user's habit (matching `prisma migrate dev`) is to run prisma commands from `apps/portal-bff/`.

Fix: indirect through `pnpm run`. `pnpm run` for a root-level script always sets cwd = workspace root regardless of where invoked from. The seed path then resolves predictably.

## What lands

| File | Change |
| --- | --- |
| `package.json` (root) | New `db:seed` npm script in `scripts` carrying the ts-node invocation. `prisma.seed` becomes `pnpm run db:seed` — the indirection forces cwd = workspace root before ts-node resolves the seed path. |

That's it. Two-line diff.

## Why `pnpm run` indirection works

| Step | cwd | Path resolution |
| --- | --- | --- |
| User invokes `pnpm exec prisma db seed` from `apps/portal-bff/` | `apps/portal-bff/` | — |
| Prisma CLI walks up, finds the workspace `package.json`, reads `prisma.seed` | `apps/portal-bff/` | — |
| Prisma spawns the seed command | `apps/portal-bff/` (inherited) | — |
| Seed command is `pnpm run db:seed` | `apps/portal-bff/` | — |
| **`pnpm run` resets cwd to the package's root (workspace root)** | **workspace root** | — |
| ts-node sees `apps/portal-bff/prisma/seed.ts` | workspace root | resolves correctly ✓ |

The same flow works if the user invokes from the workspace root — `pnpm run` still ends up at workspace root, idempotent.

## Test plan

- [ ] **Locally**: `cd apps/portal-bff && pnpm exec prisma db seed` — should report `[seed] test-tenant complete — created … Person + … User + … UserScope rows; …`. No `MODULE_NOT_FOUND`.
- [ ] **Also locally**: same command from the workspace root (`pnpm exec prisma db seed`) — same result.
- [ ] **Idempotency** — re-run, expect `created 0 Person + 0 User + 0 UserScope rows`.
- [x] No application code changed — drift gate, lint, tests untouched.
- [ ] **Review focus** — the `pnpm run` indirection trick + the cwd table above.

## Notes for the reviewer

- The deprecation warning about `package.json#prisma` (Prisma 7 migration to `prisma.config.ts`) is unchanged — not in this fix's scope.
- Could have also fixed by changing the path to be relative-to-bff (`prisma/seed.ts`) and forcing the user to run from `apps/portal-bff/`. The `pnpm run` approach is cwd-invariant — more robust to where the user invokes from.
- The new `db:seed` script is callable directly (`pnpm db:seed`) which is a small ergonomic bonus.

---------

Co-authored-by: Julien Gautier <julien.gautier@apf.asso.fr>
Reviewed-on: #234

package.json

@@ -16,7 +16,8 @@
     "grpc:sync": "node scripts/sync-ai-protos.mjs",
     "docs:dev": "vitepress dev docs",
     "docs:build": "vitepress build docs",
-    "docs:preview": "vitepress preview docs"
+    "docs:preview": "vitepress preview docs",
+    "db:seed": "ts-node --transpile-only --compiler-options {\"module\":\"CommonJS\",\"esModuleInterop\":true,\"target\":\"ES2020\"} apps/portal-bff/prisma/seed.ts"
   },
   "private": true,
   "lint-staged": {
@@ -58,7 +59,7 @@
   },
   "prisma": {
     "schema": "apps/portal-bff/prisma/schema.prisma",
-    "seed": "ts-node --transpile-only --compiler-options {\"module\":\"CommonJS\",\"esModuleInterop\":true,\"target\":\"ES2020\"} apps/portal-bff/prisma/seed.ts"
+    "seed": "pnpm run db:seed"
   },
   "devDependencies": {
     "@analogjs/vite-plugin-angular": "~2.5.0",