feat: add canonical road movements

.trellis/tasks/08-13-native-road-compiler/research/two-area-comparison.md

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+# Two-Area Native Road Comparison
+
+## Runs
+
+2026-08-14:
+
+```bash
+npm run road:compile -- --config config/areas/nantaizi-lake-innovation-valley.json
+npm run build:area -- --config config/areas/hanyang-block.json --stages intermediates
+npm run road:compile -- --config config/areas/hanyang-block.json
+```
+
+`comparison.json` is a coverage and diagnostic record. Feature counts are not
+a geometry-quality score: osm2streets and the native compiler segment roads at
+different levels.
+
+| Area | Directional roads | Native surfaces | Native junctions | Movements | Internal ends | Manual candidates | osm2streets road surfaces |
+| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
+| nantaizi-lake-innovation-valley | 34 | 19 | 6 | 46 | 4 | 2 | 50 |
+| hanyang-block | 475 | 352 | 20 | 369 | 161 | 83 | 1826 |
+
+## Observed Failure Modes
+
+The hanyang osm2streets/QGIS run completed, but its log reported repeated:
+
+- roads trimmed into oblivion;
+- degenerate intersections that could not be collapsed because layers, names,
+  highway types, or lane specifications differ;
+- intersection polygon requests with no roads.
+
+The native compiler did not hide the related uncertainty. It reported 161
+internal road ends. Eighty-three have one or more nearby, direction-compatible
+candidate departures within 35 metres; these remain suggestions for explicit
+review rather than automatic topology edits. The initial five one-way junctions
+that lacked connector curves now publish road-surface envelopes based on their
+semantic movements. Across hanyang, 369 movements are identified: 243 require
+a connector curve, while 126 are continuous at their OSM node and intentionally
+have no separate geometry.
+
+## Resulting Priorities
+
+1. Keep manual candidate suggestions and semantic overrides as the correction
+   path for near-miss topology. Do not bulk-connect candidates.
+2. Expand ordinary junction support from 3/4 physical approaches only after
+   identifying a repeated unsupported topology; one-way movements that are
+   continuous at a node are already supported without fake connector geometry.
+3. Add an inspectable movement artifact so turn geometry is not the only
+   representation of a road-to-road movement.
+4. Use a visual review of a few explicit hanyang diagnostics before changing
+   connection-distance or road-class rules.