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/configurations.md

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+# Design configurations
+
+The configuration table stores named design variants. Add parameter, feature suppression,
+physical material, and body appearance columns with `config.configure` or `config.column`.
+The desktop Configuration Table's **Add Column** menu offers the same targets. Material and
+appearance cells have a **Library** picker; their text fields also accept exact saved values.
+
+```json
+{"command":"config.configure","params":{"params":["width"],"materials":["Box1"],"appearances":["Box1"]}}
+{"command":"config.row","params":{"name":"Aluminum blue","values":{"param:width":"80 mm","material:Box1":"Aluminum","appearance:Box1":"Aluminum - Anodized Blue"}}}
+{"command":"config.activate","params":{"row":"Aluminum blue"}}
+```
+
+Use the body's actual Browser name in place of `Box1`. `config.table` returns the column keys,
+rows, active name, and `matches`: whether the current design still has the active row's values.
+Changing an assignment by hand makes `matches` false. Activating another row is undoable.
+
+Material values are names from `material.list` (case insensitive), with `Default` clearing the
+body's physical material assignment. Appearance values are names from `appearance.library`,
+an empty string or `Default` to clear the body's appearance, or a custom look object:
+
+```json
+{"command":"config.row","params":{"name":"Transparent blue","from":"Aluminum blue","values":{"appearance:Box1":{"name":"Custom blue","color":[40,90,186],"opacity":0.4}}}}
+```
+
+The table stores custom looks without losing colour or opacity. `color` contains three byte
+values, names support up to 128 Unicode characters, and `opacity` must be finite and between
+zero and one. Style values are validated when
+editing a row and again when activating a saved row. An invalid value leaves the design unchanged.
+Clearing a body appearance allows component appearance or material colour to show through;
+face appearances keep their existing priority. Physical material changes affect measured mass.
+
+`config.row` supports `from` to copy another row, `rename` to rename an existing row, and
+`delete` to remove it. Names must be unique. To remove a style column, use
+`config.column` with `material` or `appearance` set to the target body and `delete: true`.
+
+Style columns target body names. Assignments remain stored when a row suppresses the feature
+that produces that body, and become visible when it returns. Component and face appearance
+columns and conditional configuration rules are not yet supported.
+
+Designs saved with these columns use file format 7. Older designs upgrade on opening without
+changing their existing configuration values. Older SolveCraft versions must be updated to
+open newly saved designs.