feat(quality): score every face on sharpness and alignment before it is evidence

Every embedding now carries the quality of the input it came from. Both
axes fall out of the AR-005 warp for free: crop_sharpness() is the
normalised Laplacian variance over the aligned 112x112, so contrast and
size cannot leak into it, and the alignment residual is the part of the
landmark deformation a similarity transform cannot explain, so in-plane
roll reads as zero and foreshortening does not.

Carried, not consumed. Nothing discounts or thresholds on either number
yet -- that is AR-030 and VR-012, and the knee has to be located against
recorded data before a gate is chosen. What this change buys is that the
data exists to locate it with.

No face is admitted unscored: the -1 sentinel is preserved rather than
clamped, and a degenerate landmark fit is counted rather than silently
dropped.

Takes the VR-001 dump to schema_version 2. The bump is not for readers,
which check for the datasets by name and replay a v1 dump unchanged; it
is so a consumer can tell "never scored" from "scored zero", which is
not recoverable from the arrays afterwards.

TRACES: AR-028, AR-029, AR-030 | VR-001 | SR-002

src/types.hpp

@@ -59,11 +59,36 @@ inline constexpr float kArcFaceRef[5][2] = {
 // Landmark order matches ArcFace convention (same as SCRFD output order):
 //   [0] right-eye-centre  [1] left-eye-centre  [2] nose
 //   [3] right-mouth       [4] left-mouth
+/// TRACES: AR-028 | SR-002
 struct DetectedFace {
     cv::Rect2f                   bbox;
     std::array<cv::Point2f, 5>   landmarks;
     float                        confidence{0.f};
 
+    // ── AR-028 quality vector ────────────────────────────────────────────────
+    // Three axes, kept separate and never collapsed into one scalar: they fail
+    // for different reasons, have different remedies, and do not earn the same
+    // response. Carried, not consumed — the vector travels with the face into
+    // the VR-001 dump so a threshold can be re-litigated against recorded data
+    // rather than by re-running video.
+    //
+    // **Size is the third axis and is deliberately not a field here.** It is
+    // `bbox`, which every consumer already has, scaled by the frame's
+    // `bbox_upscale` to reach the original resolution AR-002 thresholds in.
+    // Copying it into a second field would put the same quantity in two
+    // coordinate spaces inside one struct — the trap SCHEMA.md records for
+    // `bbox_upscale` — and the copy would be the one that drifts.
+    //
+    // Both fields below are -1 until the aligner runs, so *unscored* is
+    // distinguishable from *scored badly*. Nothing downstream may read a
+    // negative value as a quality.
+
+    // AR-029 sharpness: normalised Laplacian variance over the aligned crop,
+    // dimensionless. Falls with motion blur and soft focus; invariant to
+    // contrast, and taken on the fixed 112×112 canvas so it cannot re-measure
+    // face size. See crop_sharpness() for the construction and its one hazard.
+    float                        sharpness{-1.f};
+
     // AR-030 visibility: RMS landmark misfit, in canonical 112×112 pixels, left
     // over after the best similarity fit to the ArcFace template. Rises with
     // out-of-plane pose and with occlusion; blind to in-plane roll and to face