docs: audit findings, verification tiers, CI image, artifact storage

Corrections from the dump audit and the completed agent work:

- AR-010 is not started, not in progress: is_scene_boundary has no producer
  anywhere. SceneDetectorFunc is a terminal sink writing scenes.json and never
  annotates the frame, so the field is permanently false and the dump column a
  constant 0. A replay test of the frame-dependent track_alpha would pass
  vacuously — the worst failure mode for a verification gate.
- T1 (functor-level) becomes the primary verification tier, not T2. KPN node
  functors are plain callables constructed outside the network, so a node is
  tested by calling operator() with hand-built inputs. That removes four
  hazards at once: fixture provenance, replay-from-frame-0, cross-test state
  leakage, and replay-harness nondeterminism. It also means a dead upstream
  producer no longer blocks testing its consumer.
- VR-010 (dump provenance) and VR-011 (replay harness rewrite) added. A dump
  made with LVFace is currently byte-indistinguishable from one made with
  w600k-R50 — the GR-004 problem again, in the dump.
- Four requirements had no verification tier at all; the traceability gate
  found them.
- DP-007: CI builder image, CPU-only, pinned by tag in the Gitea container
  registry. Corpus fixtures go to the package registry rather than LFS: LFS is
  pulled on clone and would tax every developer for data only CI reads.
- IR-004/005/007/008 marked done; the v1 DSP parameters they had to pin are
  now normative in the server spec.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

TRACES: AR-010, DP-007, IR-004, IR-005, IR-007, IR-008, VR-001, VR-010, VR-011 | SR-002, SR-003

docs/SPEC.md

@@ -154,6 +154,26 @@ Two distinct signals, deliberately kept separate:
 - **`is_scene_boundary`** — opt-in (`--scene-detect`). TransNetV2 over a densely
   decoded, downscaled stream flags a *true shot/scene boundary*.
 
+> **`is_scene_boundary` currently has no producer.** `grep -rn is_scene_boundary
+> src/` finds no assignment anywhere: `SceneDetectorFunc` is a *terminal sink*
+> (`main.cpp:298-300`, `kpn::out<>`) that writes `scenes.json` and never
+> annotates the `Frame` flowing to the face pipeline. The field is therefore
+> always `false`, and the dump column (`embedding_dump_node.hpp:38`) is a
+> constant 0. Compounding it, `main.cpp:280` returns from the
+> `--dump-embeddings` branch *before* the `scene_detect` branch at `:296`, so no
+> dump-producing path even instantiates the detector.
+>
+> This makes AR-010 **not implemented**, not "in progress" — and it means a T2
+> test of the frame-dependent `track_alpha` (AR-007) would **pass vacuously**,
+> which is the worst possible failure for a verification gate. The fix is in the
+> producer, not the schema: make `SceneDetectorFunc` a pass-through (or add a
+> boundary annotator before the decimator) and add the scene branch to
+> `dump_embeddings.cpp`. **No `schema_version` bump** — the column exists and
+> merely stops being constant.
+>
+> Fixtures generated before the fix must be marked in provenance, since `0` is
+> presently indistinguishable from "no boundary here".
+
 Both feed AR-007 as **association hints**: they tell the tracker that spatial
 continuity is broken and that association should weight embedding over IoU.
 Neither ends a presence window (AR-012).
@@ -770,6 +790,54 @@ prerequisite.
 
 **Gap:** installer unbuilt.
 
+## DP-007 — CI build image
+
+CI runs on an Intel N100 with no discrete GPU, so the test build must configure
+**CPU-only** and must not require CUDA, TensorRT or ROCm:
+
+```
+-DSAE_INFERENCE_BACKEND=ORT  -DSAE_GEMM_BACKEND=CPU
+```
+
+A prebuilt container image supplies the toolchain, published to the **Gitea
+container registry** and pinned by tag — matching the `jellytau-builder`
+precedent. Building dependencies per CI run is untenable on an N100, and OpenCV 5
+from source would dominate every run.
+
+The same registry stores corpus dump fixtures as generic packages (see the
+fixtures table in `requirements.md`). Rebuild the image when its dependency set
+changes, not per run, and pin CI to a tag rather than `latest` so a rebuild
+cannot silently change what a green build meant.
+
+**Required in the image:**
+
+| Dependency | Why |
+|---|---|
+| CMake, C++ toolchain, pkg-config | Build |
+| **OpenCV 5** | `CMakeLists.txt:25` prefers 5, falls back to 4. The branch targets 5, so the image should carry it — it is not yet in most distro repos and building it per-run is prohibitive |
+| HDF5 (C++) | Galleries are HDF5-native; also the dump format |
+| FFmpeg dev libs — `libavformat`, `libavcodec`, `libavutil`, `libswscale`, **`libswresample`** | Decode. See the note below on swresample |
+| Python 3 + numpy, h5py, scipy | Python-side tests, replay, traceability tooling |
+| Catch2, nlohmann/json | **Vendored into the image, not fetched.** Both are `FetchContent`-ed today (`CMakeLists.txt:220`, `tests/CMakeLists.txt:8`), which makes every CI run depend on GitHub reachability |
+
+**Deliberately excluded:** CUDA, TensorRT, ROCm — no GPU to use them. Also the
+ONNX Runtime *GPU* providers; only the CPU provider is relevant, and only for T3
+smoke tests.
+
+**Models are not baked into the image.** The seven ONNX files total ~725 MB and
+live in Git LFS. T1/T2 tests are model-free by design
+(`tests/CMakeLists.txt:1-4`), so the default image needs none. T3 smoke tests
+require a model and should pull it via LFS in a separate job rather than
+inflating the image tenfold for a minority of tests.
+
+**`libswresample` is a real gap, not a formality.** The current
+`pkg_check_modules` list (`CMakeLists.txt:200-203`) covers avformat, avcodec,
+avutil and swscale but **not** swresample — which IR-004 needs to downmix to mono
+and resample to 11025 Hz. It must be added alongside the audio-signature work.
+
+**Gap:** entire requirement. The image does not exist, and no CI config is
+present in this repo.
+
 ## DP-006 — Gallery maintenance as a background concern
 
 - Incremental gallery refresh runs on a timer (`gallery_scan_interval`, default