chore(task): archive 08-14-native-road-lane-markings

.trellis/tasks/archive/2026-08/08-14-native-road-lane-markings/implement.md

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+# Implementation Plan
+
+1. Add reusable template-placement helper to the existing turn-arrow module,
+   preserving its supported-asset gate and output ring shape.
+2. Extend the native compiler with lane-separator, repeated road-direction
+   arrow, and explicit-turn-arrow polygon generation plus source diagnostics
+   and layer persistence.
+3. Extend native output records/counts and Blender adapter mappings. Reuse
+   existing `lane_separators` and `lane_arrows_webscale` materials only.
+4. Add Workbench layers, toggles, selection/provenance inspector entries, and
+   preserve the existing Workbench-only direction triangle behavior.
+5. Add focused fixtures for supported turn placement, unsupported maneuver,
+   short approach skip, and separator geometry; run native/workbench/build
+   stage tests.
+6. Build Nantaizi with `blender,cesium,preview --road-provider native`, inspect
+   the final preview, and confirm no `package/` publication occurred.
+
+## Validation
+
+```bash
+npm run test:native-road
+npm run test:road-workbench
+npm run test:turn-lane-arrows
+npm run test:build-stages
+npm run road:compile -- --config config/areas/nantaizi-lake-innovation-valley.json
+npm run build:area -- --config config/areas/nantaizi-lake-innovation-valley.json \
+  --stages blender,cesium,preview --road-provider native
+```
+
+Rollback is selecting `--road-provider osm2streets`; no existing output path
+is replaced.