feat: strengthen modeling, configuration, and assembly workflows

Preserve linked sketch identities through deterministic face projection and resizing. Fix origin-corner picking, persistent inline navigation, appearance editing, configuration styles, component properties, contact sweeps, sheet exports, analytic STEP offsets, and bounded rolling-ball fit accuracy.

Validated with full cargo xtask ci, native workflow screenshots, repeated enclosure replays, and analytic geometry regressions.

docs/assembly-properties.md

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+# Assembly physical properties
+
+The Browser's component **Properties** action measures the selected assembly placement,
+including its nested components. Select the root design to measure every instance in the
+assembly. The window shows material-aware mass, volume, surface area, center of mass and
+the world bounding box. Pending occurrence moves are included without capturing them.
+
+The same measurements are available through commands:
+
+```json
+{"command":"component.properties","params":{"component":"Bracket"}}
+{"command":"component.properties","params":{"component":"root"}}
+{"command":"component.properties","params":{"component":"Subassembly","descendants":false}}
+{"command":"occurrence.properties","params":{"occurrence":"Bracket:2"}}
+```
+
+`component.properties` defaults to the active component and measures its first placement.
+`occurrence.properties` measures the chosen instance. A nested occurrence can appear beneath
+several instances of its parent; supply `path` (the complete list of occurrence ids from the
+root) to choose one of those placements. An ambiguous occurrence without a path returns an
+error. Both commands accept `descendants: false` to measure only directly owned bodies.
+
+Results contain a `bodies` list and a `total` object. Each body's entry identifies the original
+body name, owning component and occurrence path. Physical material density is resolved from
+that original body, so copies keep their material and mass. Values use millimetres, square
+millimetres, cubic millimetres and grams; coordinates use the world frame.
+
+Mass and center of mass account for each body's density. Volume and area are summed over
+placed bodies, including overlapping bodies and repeated instances. Measurements use the
+kernel's tessellation-based body measurement. An empty component reports zero totals and
+null center of mass and bounding box. A failed body measurement returns an error instead of
+presenting an incomplete assembly total. These commands leave geometry, pending placements
+and undo history unchanged.