fix(887): the image build builds the SPA and does not test it

`docker/Dockerfile`'s web-build stage is gitless twice over — the build context is
`web/` + `design-system/` so there is no `.git`, and `node:22-bookworm-slim` ships no
git binary. Members of the SPA suite need one or the other, so running the suite there
required naming the ones that cannot run. That list was a population nothing derived:
#883 added a third member without updating the hand-written pair of `--exclude`s, and
because `Build & push image (amd64)` is `if: github.event_name != 'pull_request'` the
resulting red was unreachable on a PR. It landed on `main` and on the `v*` tag path
instead — every image build failed, `:latest` stopped being republished, and a release
cut would have failed at the image build.

Adding a third `--exclude` re-arms the trap, so the list is removed rather than
extended: the stage now lints, typechecks and BUILDS the SPA, and the suite runs once,
unfiltered, in `docker-build.yml`'s `test` job on a real checkout. `build` carries
`needs: [test, migrations, scan]`, so no image is published past a red suite.

`scripts/tests/test_image_build_delegates_the_spa_suite.py` holds both halves — the
negative one alone would be satisfied by deleting the `needs:` edge. Three populations,
all derived: tracked Dockerfiles and workflows from the git index, and which npm scripts
ARE the suite from `web/package.json` (so `test` is in and the Playwright `test:ui-e2e`
is out, with no exemption list). Publishing jobs come from the `docker/build-push-action`
step and the Dockerfile each builds from that step's own `file:` input, which is why
`ci-image.yml` is out of scope by derivation rather than by an entry that would outlive
its reason.

Four mutants witnessed red, each by the intended test: a filtered suite run put back
into the Dockerfile, the `needs:` edge deleted, and the gating run narrowed in both the
block and the single-line `run:` step forms.

Refs: #887
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019T79beF1Ufid3dXju4yqkF

docs/testing.md

@@ -20,7 +20,7 @@ before adding tests, not just `docs/contributing.md` §8 (which now just points
 | `ErsatzTV.Scanner.Tests` | Library scanning: scan handlers, folder scanners, NFO readers | Handler tests substitute the folder scanners + `ILibraryRepository` and assert the resulting repository writes (e.g. `ScanLocalLibraryHandlerTests` pins which `LastScan` levels a scan records — ersatztv#264). Fakes/`Testably` back the file-system-facing scanners. ~1,485 tests (approximate on purpose — an exact count goes stale on every PR that adds one). Additionally contains `Core/FFmpeg/TranscodingTests` — `[Explicit]` + `[Combinatorial]`, so it never runs in CI or a plain `dotnet test` (it needs real ffmpeg/hardware) and contributes 0 to that count; run it by name when touching the transcoding pipeline. |
 | `ErsatzTV.Architecture.Tests` | Layering rules via NetArchTest.eNhancedEdition | Core↛Infra/App/EF; FFmpeg↛all; App↛concrete providers. 5 tests. See `docs/contributing.md` §1. |
 | `ErsatzTV.FFmpeg.Tests` | FFmpeg command construction | Build a pipeline, assert the exact rendered arg string (`PipelineBuilderBaseTests.cs`). |
-| `web/` (vitest) | React SPA unit tests | Run alongside typecheck + build (see below). Collects `src/**`, `web/scripts/**` *and* `web/vite-plugins/**`, but deliberately **excludes** `web/e2e/**` (the Playwright specs — vitest's default `**/*.spec.*` glob would otherwise run them under jsdom). Two files have git prerequisites since ersatztv#819. `web/src/api/pageSizeCallSites.guard.test.ts` needs a git **checkout** AND, through it, the **binary** — it derives its file population from `git ls-files` via `web/vite-plugins/trackedSourceFiles.ts` rather than a directory walk, and refuses rather than falling back. `web/vite-plugins/trackedSourceFiles.realgit.test.ts` needs the **binary** but no checkout: it builds its own temp repository to prove that derivation by executing it. So it is not checkout-versus-binary — supplying a `.git` alone would not let either run. Every other file runs fine with neither. `docker/Dockerfile`'s web-build stage runs the suite with exactly those two `--exclude`d, because its context carries no `.git` and `node:22-bookworm-slim` ships no git — and the two exclusions overlap rather than divide — both files need the binary. |
+| `web/` (vitest) | React SPA unit tests | Run alongside typecheck + build (see below). Collects `src/**`, `web/scripts/**` *and* `web/vite-plugins/**`, but deliberately **excludes** `web/e2e/**` (the Playwright specs — vitest's default `**/*.spec.*` glob would otherwise run them under jsdom). Some files have git prerequisites since ersatztv#819, and the set is not fixed — ersatztv#883 added one. `web/src/api/pageSizeCallSites.guard.test.ts` and `web/src/api/completeAnnotations.guard.test.ts` need a git **checkout** AND, through it, the **binary**: they derive their file population from `git ls-files` via `web/vite-plugins/trackedSourceFiles.ts` rather than a directory walk, and refuse rather than falling back. `web/vite-plugins/trackedSourceFiles.realgit.test.ts` needs the **binary** but no checkout — it builds its own temp repository to prove that derivation by executing it. So it is not checkout-versus-binary: supplying a `.git` alone would not let any of them run. **The suite therefore runs only where git is present, and `docker/Dockerfile` is not such a place** — its web-build stage builds the SPA and does not test it (ersatztv#887). Enumerating the git-dependent files as Docker `--exclude`s was tried and REVERSED: that list is a population nothing derives, it went stale the first time a guard was added, and the resulting red is unreachable on a PR — `Build & push image (amd64)` is `if: github.event_name != 'pull_request'` — so it landed on `main` and on the release tag instead. The image is gated on `docker-build.yml`'s `test` job running the whole suite on a real checkout, held by `scripts/tests/test_image_build_delegates_the_spa_suite.py`. |
 | `web/e2e/` (Playwright) | UI-interactive E2E flows against a **live** instance | Not a unit suite and **not** part of `npm test` — needs a running server, so it runs via `scripts/e2e-ui.sh` (boots its own fresh instance) and in CI as a step of the `functional-e2e` job. Headless Chromium, `serial`, `retries: 0`. Scope rule: assert only what the curl harness structurally cannot. See `docs/e2e-local.md` → "UI-E2E harness". |
 
 ## Golden-file nets