## Summary
First implementation step of ADR-0018. Create [`src/environments/environment.ts`](apps/portal-shell/src/environments/environment.ts) holding the two SPA per-environment values the ADR calls out — `bffApiBaseUrl` and `otlpEndpoint` — and replace the hard-coded URLs at the two SPA call sites that needed them.
## What changes
- **New `environment.ts`** with dev defaults (`http://localhost:3000/api` and `http://localhost:4318/v1/traces`). Header comment links to ADR-0018, documents the constraint that per-environment siblings must share the same shape, and notes that nothing here is a secret (the SPA bundle is public).
- **`observability/tracing.ts`** reads `environment.otlpEndpoint` for the exporter, and **derives** the `propagateTraceHeaderCorsUrls` regex from `environment.bffApiBaseUrl` — a future change to the BFF origin propagates `traceparent` to the right host automatically, no second edit needed.
- **`home-status.service.ts`** builds `/health` as `${environment.bffApiBaseUrl}/health`.
## What this PR explicitly does NOT do
- **No `environment.staging.ts` / `environment.prod.ts`** yet. The ADR says "ship later" for those, and the real prod / staging URLs are unknown until the infrastructure ADR lands. Dropping plausible-but-wrong URLs into the repo would be worse than waiting.
- **No `fileReplacements` configuration in `project.json`** — it depends on the per-environment files existing. Wired in the same PR that introduces them.
- **No BFF-side audit pool split** (`AUDIT_DATABASE_URL` validator, second Prisma client, boot-time UPDATE-rejection self-test). Also in the ADR's Confirmation list, but it touches `AuditModule` and deserves its own review. Separate PR.
- **No `SERVICE_VERSION` wiring** in `tracing.ts`. Still hard-coded to `'dev'`; the build-time version source (same one that will feed the footer's dev-only version badge) is its own small chantier.
## Test plan
- [x] `pnpm exec nx run-many -t lint test build --projects=portal-shell` — green (36 / 36 specs unchanged, no new tests needed).
- [x] Production build size unchanged (121 kB gzip initial — `environment.ts` is one literal object inlined by the bundler).
- [ ] Manual: `pnpm exec nx serve portal-shell` → home page loads, the health widget hits the BFF, Jaeger shows the SPA `document_load` + `fetch` + BFF child span trace.
- [ ] Manual: temporarily change `bffApiBaseUrl` to `http://localhost:9999/api` → the fetch fails (expected), and the `traceparent` propagation regex no longer matches `:3000` (verifiable in Network panel — header is absent on cross-origin requests).
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Co-authored-by: Julien Gautier <julien.gautier@apf.asso.fr>
Reviewed-on: #90
julien
8f125d2a90