feat: add Nepal flood incident scene

public/events/bhote-koshi-2026/README.md

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+# Bhote Koshi 2026 event pack
+
+A non-commercial visualization of the 26 August 2026 Bhote Koshi outburst flood.
+This is not an official hazard model.
+
+## Provenance and licenses
+
+| File | Source and modifications | License |
+| --- | --- | --- |
+| `pre.webp` | Vantor WorldView-2 scene `10300100C86CED00`, observed 2021-10-16; natural-color crop of 85.295–85.379 E, 28.135–28.292 N, resampled to 2048×4352 and WebP-compressed | CC BY-NC 4.0 |
+| `post.webp` | Vantor WorldView-3 scene `B040001100881410`, observed 2026-08-27; same bounds and output geometry, with source clouds retained | CC BY-NC 4.0 |
+| `event.json` | GeoPera reconstruction, commit `59ee5bd`; every fourth published centerline point inside the image bounds, plus sixteen curated evidence records linking public witness posts and the GeoGeorgeShadrach geolocation map | CC BY-NC 4.0 for the derived centerline; linked posts and map records retain their owners' terms |
+| `src/data/bhoteKoshiFloodPath.js` (outside this directory) | Simplified GeoPera centerline from the Debris-Dammed Lake observation to Trishuli Bazaar, compiled into the scene and locator | CC BY-NC 4.0 for the coordinate dataset, separately from the executable code |
+
+These third-party assets are **not covered by the application's MIT license**.
+Keep attribution and the [CC BY-NC 4.0 license](https://creativecommons.org/licenses/by-nc/4.0/).
+For commercial use, obtain separate permission or exclude both this pack and the
+derived coordinate dataset in `src/data/bhoteKoshiFloodPath.js` from the source
+and build. Deleting this directory alone does not remove the compiled river
+data. Excluding the Nepal scene also requires removing its registrations and
+imports before building.
+
+Sources:
+
+- [Vantor Open Data Program](https://vantor.com/company/open-data-program)
+- [Historical source image](https://vantor-opendata.s3.amazonaws.com/events/Nepal-Flooding-Aug-2026/10300100C86CED00.tif)
+- [Post-event source image](https://vantor-opendata.s3.amazonaws.com/events/Nepal-Flooding-Aug-2026/B040001100881410.tif)
+- [GeoPera reconstruction](https://github.com/geo-pera/bhotekoshi-2026-reconstruction)
+- [GeoGeorgeShadrach public geolocation-map introduction](https://x.com/geogeorgeology/status/2093632283442053371)
+
+Witness clips and cached posters are not bundled. Cards link to the original
+source, or use the original platform's embed where available. An unavailable
+embed leaves the source link accessible. Capture times remain unverified.
+
+Esri basemap imagery and runtime terrain are fetched separately, not bundled;
+their provider attribution remains visible in the application.
+
+The Nepal sequence supports both keyed and keyless map setups. Google 3D is used
+for authored 3D shots when available; otherwise those shots use Esri imagery.
+Without a Cesium ion token, terrain comes from Re:Earth / Mapterhorn. With an
+ion token, the configured Cesium terrain remains available. Vantor comparison
+shots use Esri in either mode. Provider resolution does not rewrite saved shots.
+
+## Interpretation limits
+
+The 2021 image is historical context, not an immediate pre-event baseline.
+Differences also span development, seasons, sensors, and the July 2025
+Rasuwagadhi flood. The amber corridor is a schematic progression along the
+published river centerline, not modeled arrival time. Its width and timing
+must not be used for emergency planning, exposure analysis, or casualty claims.
+
+Evidence cards identify observations outside the Vantor comparison rectangle.
+The Rasuwagadhi witness focus uses the 2021 context image because the 2026
+scene does not provide useful coverage at that point. The Timure record groups
+five source-map placements, not five independent timing confirmations.