Add PathStyleExtension Seattle road data

examples/path-style-extension/README.md

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+# PathStyleExtension Seattle road diagram
+
+This directory contains the pinned City of Seattle data used by deck.gl's `PathStyleExtension`
+street-design example at Dexter Avenue N and Thomas Street.
+
+## Files
+
+- `data/seattle-road-diagram.json` contains render-ready path and polygon assets for the example.
+- `scripts` contains the reproducible extraction and validation tools.
+
+The extractor also writes a provenance manifest and audit report next to the snapshot. Both are
+ignored because they are reproducible and are not used by the example.
+
+The runtime snapshot contains only the normalized geometry, styles, tooltip fields, and source
+links consumed by deck.gl. Raw ArcGIS responses are queried and validated during extraction but are
+not shipped to the website. Roads and sidewalks share one ordered surface collection, while curbs
+and pavement symbols share one ordered detail collection.
+
+From the repository root, validate the checked-in snapshot with:
+
+```bash
+node examples/path-style-extension/scripts/validate-seattle-road-diagram.mjs
+```
+
+City of Seattle Department of Transportation data is used under the Public Domain Dedication and
+License (PDDL) 1.0. See the extraction-script README for complete source details.

examples/path-style-extension/data/.gitignore

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+seattle-road-diagram.manifest.json
+seattle-road-diagram-report.md

examples/path-style-extension/scripts/README.md

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+# PathStyleExtension Seattle road-diagram data
+
+These scripts create and validate the pinned data snapshot used by the
+[`PathStyleExtension` street-design example](https://github.com/visgl/deck.gl/tree/master/examples/website/path-style-extension).
+The website never queries the live City of Seattle ArcGIS services.
+
+From the repository root:
+
+```bash
+node examples/path-style-extension/scripts/score-candidate-sites.mjs
+node examples/path-style-extension/scripts/extract-seattle-road-diagram.mjs
+node examples/path-style-extension/scripts/validate-seattle-road-diagram.mjs
+```
+
+The scripts read and write the adjacent `examples/path-style-extension/data` directory by default.
+
+The extractor pages a bounded query by sorted object ID, requests WGS84 GeoJSON, and records the
+exact page URLs and hashes in a machine-readable manifest and human-readable audit report. It
+publishes a compact runtime snapshot whose path and polygon collections already contain the
+geometry, dimensions, dash patterns, tooltip fields, and source links consumed by the example.
+
+The render-ready output includes two documented cartographic derivations and one topology-repaired
+display representation:
+
+- equal-width approach lane bands from Seattle Streets centerlines and nearby 12-foot `LaneWidth`
+  records;
+- justified crosswalk guides from in-service Marked Crosswalk points and Seattle Streets surface
+  widths. The extractor records which source stripe polygons each guide replaces in the display so
+  the same crosswalk is not painted twice.
+- continuous pavement-symbol paths by joining CAD fragment endpoints no more than 2 millimeters
+  apart. Every source coordinate is retained, and any nonzero bridge is recorded in the manifest.
+
+Source geometry used by the runtime assets is not simplified, manually redrawn, or snapped. Raw
+source layers remain reproducible through the recorded queries but are not included in the
+checked-in runtime snapshot. The snapshot is for demonstrating deck.gl and is not suitable for
+engineering, construction, legal interpretation, or navigation.
+
+## Sources
+
+- [Thomas Street project](https://www.seattle.gov/transportation/projects-and-programs/programs/greenways-program/thomas-st-5th-ave-n-to-dexter-ave-n)
+- [SDOT protected-intersection update](https://sdotblog.seattle.gov/2024/05/10/thomas-and-dexter-protected-intersection-update/)
+- [SDOT Channelization FeatureServer](https://services.arcgis.com/ZOyb2t4B0UYuYNYH/arcgis/rest/services/SDOT_Channelization_view/FeatureServer)
+- [Seattle Streets](https://catalog.data.gov/dataset/seattle-streets)
+- [Sidewalks](https://catalog.data.gov/dataset/sidewalks-32d94)
+- [Marked Crosswalks](https://catalog.data.gov/dataset/marked-crosswalks)
+- [Existing Bike Facilities](https://catalog.data.gov/dataset/existing-bike-facilities)
+- [SDOT GIS datasets and public-data terms](https://cos-data.seattle.gov/Transportation/SDOT-GIS-Datasets/jyjy-n3ap)
+
+City of Seattle Department of Transportation data is used under the Public Domain Dedication and
+License (PDDL) 1.0 and remains subject to the city's accuracy and service-availability disclaimers.