feat(registry): bring back the video-primitive moves (#3169)

Restores the 208 catalog items reverted after their previews 404'd in
production, this time on the payload mechanism rather than the .html files
that caused the outage.

The generator no longer writes a preview document to docs/public. That writer,
and the machinery under it, existed only to produce files the docs host
discards, so it is gone rather than bypassed. Items now embed the composition
itself via a payload, which is what the previous change already does for the
items that were already in the catalog.

The variables explorer is parked, not restored: it drove its preview through
the same unpublished .html path, so it would have shown an empty frame. Items
that declare variables get the live player plus the static variables table, and
reconnecting the explorer to payloads is a follow-up.

registry/components/segmentation-flood/registry-item.json

@@ -0,0 +1,84 @@
+{
+  "$schema": "https://hyperframes.heygen.com/schema/registry-item.json",
+  "name": "segmentation-flood",
+  "type": "hyperframes:component",
+  "title": "Segmentation Flood",
+  "description": "Machine-vision read of a slotted subject: translucent accent segmentation masks flood on in quantized scanline steps, each region gets a thin bracket and mono label chip, a deterministic 2-frame HUD flicker rides the pass, then the labeled read settles clean.",
+  "tags": [
+    "motion-primitive",
+    "product-demo",
+    "ai",
+    "hud",
+    "canvas",
+    "deterministic",
+    "experiment"
+  ],
+  "jobs": ["demonstrate"],
+  "family": "product-demo",
+  "profile": "machine-read",
+  "evidence": "Wave M3 experiment slate; gmunk segmentation contact sheet 2031767296331702694/sheet-02 (red masks flooding in scanline steps under HUD flicker), tokenized",
+  "syncPoints": [{ "id": "flood", "phase": "in", "offset": 0.8 }],
+  "files": [
+    {
+      "path": "segmentation-flood.html",
+      "target": "compositions/components/segmentation-flood.html",
+      "type": "hyperframes:snippet"
+    }
+  ],
+  "variables": [
+    {
+      "id": "regions",
+      "type": "string",
+      "role": "content",
+      "label": "Regions",
+      "description": "Comma-separated region labels; 2 to 4 are used, one translucent mask + bracket + mono chip each.",
+      "default": "Figure, Signal, Ground"
+    },
+    {
+      "id": "flood_at",
+      "type": "number",
+      "role": "timing",
+      "label": "Flood at",
+      "description": "Seconds from mount start when the segmentation pass begins. Clamped so the pass and any exit stay inside the clip.",
+      "default": 0.8
+    },
+    {
+      "id": "flicker",
+      "type": "enum",
+      "role": "style",
+      "label": "Flicker",
+      "description": "Deterministic 2-frame HUD luminance toggle riding the flood pass.",
+      "default": "on",
+      "options": [
+        { "value": "on", "label": "On" },
+        { "value": "off", "label": "Off" }
+      ]
+    },
+    {
+      "id": "accent",
+      "type": "enum",
+      "role": "style",
+      "label": "Accent",
+      "description": "Mask, bracket, and chip color: green rides --brand, blue rides --accent, violet rides --accent-2.",
+      "default": "green",
+      "options": [
+        { "value": "green", "label": "Green" },
+        { "value": "blue", "label": "Blue" },
+        { "value": "violet", "label": "Violet" }
+      ]
+    },
+    {
+      "id": "exit",
+      "type": "enum",
+      "role": "timing",
+      "label": "Exit",
+      "description": "Optional departure. Default none: the labeled read holds until the frame cuts.",
+      "default": "none",
+      "options": [
+        { "value": "none", "label": "None" },
+        { "value": "fade", "label": "Fade" },
+        { "value": "up", "label": "Up" }
+      ]
+    }
+  ]
+}