[RNE Rewrite] test(ts): add API tests for the TypeScript surface - #1355

- `core/`: tensor byte semantics and copy windows, model execution and
  disposal, `wrapAsync` error propagation, and the spec matcher in depth —
  symbol binding, variant selection, runtime-constraint matching, and the
  authoring errors that fire before matching starts.
- `fetcher/`: caching, forced re-download, byte-weighted progress, HTTP and
  transport failures, cancellation, requests shared between concurrent callers,
  iOS partial-file resume, and the Android DownloadManager backend. Telemetry
  gets its own suite, including the locale parsing that must not read a
  language-only tag as a country.
- `extensions/`: box and point scaling under both resize modes, box decoding,
  and the seeded generators.

One suite per pipeline: which model signatures it accepts, that a mismatch is
rejected with a message naming the mismatch, the postprocessing that is the
pipeline's own work (softmax ordering, NMS suppression, argmax colormaps,
sigmoid grayscale masks, coordinate scaling back through letterboxing), every
option and per-call override, and that `dispose()` releases everything.

The pipelines whose behavior depends on real model weights — Whisper, VAD,
SDXS, keypoints, instance segmentation — get schema acceptance, rejection and
full disposal instead, including Whisper's nested tokenizer and VAD pipeline.

`tasks/constructionFailure.test.ts` records a leak the suites surfaced: a
`create<Task>` factory that throws after `loadModel` abandons the native model,
and the caller never receives a `dispose` to release it. The tests assert the
current behavior so it flips loudly once fixed.

Hook suites cover the lifecycle apps depend on: disposal on unmount and on
config change, the create-after-unmount race, config identity by value,
download cache hits, preventLoad, and errors surfaced through the shared field.

- A snapshot of every export, so an addition, rename or removal shows up in the
  diff of the pull request that causes it rather than in a user's app.
- Registry rules that only fail on a device otherwise: https URLs on the
  software-mansion org, a pinned revision, the
  `modelname_backend_precision.pte` naming contract, a folder matching the
  backend suffix, and a default alias structurally identical to one of its own
  variants.
- Label-array invariants, including the ImageNet duplicates that must stay
  because the array mirrors the model's output vocabulary.
- Source-level conventions, parsed with the TypeScript compiler: the
  `'worklet'` directive on every JSI wrapper, and the core/extensions and
  hooks/native import boundaries from the architecture guide.

Adds an `api-tests` job to CI — no native libraries, no simulator, no `.pte`,
so the existing TypeScript-only setup action is all it needs.

Adds an `add-api-tests` skill covering the fake runtime, the helpers, what to
cover for a new pipeline or hook, and the leak-checking contract; wires it into
the skills index, the architecture guide and the maintenance list; and adds the
test step to the verify-and-build workflow and checklist.

Also refreshes the hook example in `add-task-pipeline`, which still showed the
`localPath` shape from before the resource fetcher landed.

Rebasing onto the supertonic TTS pipeline (#1317) surfaced two gaps the suites
themselves reported:

- The registry walk assumed every task config names a single `modelPath`.
  Supertonic assembles four `.pte` files under `modelPaths`, so its category
  looked empty and its variant group went unchecked. Recognize both shapes, and
  compare variants on the whole set of files they name.
- The export snapshots record the new TTS surface. Additions only — no removal
  or rename.

Adapts the suites to what landed on `rne-rewrite` since they were
written: hooks report absence as `undefined` rather than `null`, aborts
surface as a coded `DOWNLOAD_ABORTED` rather than an `AbortError` class,
`schema.constr` is now `schema.constraint` with `equality` in place of
`eq`, the CV ops moved to singular module names, `bool` joined `DType`,
and the iOS download path reads its status through blob-util's
`stateChange`, which the mock now serves.

Two registry conventions were restated rather than relaxed. Variant
groups name their default with an explicit `DEFAULT` key instead of
spreading it, and a default may now live further down the tree (a YOLO26
family defaults through a scale and an input size), so the rule is that
the default has to be a config the group actually offers. Model files
are still required to declare their backend and precision, but Kokoro
nests a variant folder under the backend one and publishes its
grapheme-to-phoneme models per language, so the backend is looked for
anywhere in the path and the untagged files are pinned to that one
shape rather than left to opt out silently.

The three source fixes the suites originally carried are all upstream
already, so the commit that made them is gone.