M3.72: Tile Edge Color dialog and Show Swatch Bounds in pattern editing

Object > Pattern > Tile Edge Color... picks the colour of the tile edge
(a layer-colour preset or a custom colour), stored in the preference
patternTileEdgeColor and passed to the renderer. Pattern Options gains
Show Swatch Bounds: a dashed outline of the part of the tiling the swatch
repeats (the period of brick and hex tilings).

Commands: prefs.set {patternTileEdgeColor}, pattern.options
{showSwatchBounds}, ui.tileEdgeColor. Model: PatternDef.show_swatch_bounds.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/control-protocol.md

@@ -90,3 +90,7 @@ Add to Swatches.
 opening a `.vcswatches` or `.gpl` file with `app.open` does the same. `ui.saveSwatchLibrary {names?}` opens the
 `saveSwatchLibrary` dialog (fields `name`, `format`: `vcswatches`/`gpl`/`css`, `user`: save to the user library
 folder, `selectedOnly` with `names`); `ui.dialog.confirm` runs `swatch.library.save` (to a file it asks for a path).
+
+Tile Edge Color: Object → Pattern → Tile Edge Color… (`ui.tileEdgeColor`) opens the `tileEdgeColor` dialog (field
+`color`: `#rrggbb` or a preset name such as "Light Blue"); `ui.dialog.confirm` sets the preference
+`patternTileEdgeColor` (`prefs.set`), the colour pattern editing mode draws the tile edge and the swatch bounds in.

docs/mcp.md

@@ -371,4 +371,14 @@ that split into many regions. The result reports `{ids, vector, rasterized, opti
 ```json
 {"name":"run_command","arguments":{"command":"object.flattenTransparency","params":{"ids":[12,15],"preset":"high"}}}
 {"name":"run_command","arguments":{"command":"object.flattenTransparency","params":{"balance":0,"lineArtPpi":150}}}
+
+## Pattern editing display
+
+In pattern editing mode the tile edge (`pattern.options {showTileEdge}`) and the swatch bounds (`pattern.options
+{showSwatchBounds}`: the part of the tiling the swatch repeats, dashed) are drawn in the preference
+`patternTileEdgeColor`.
+
+```json
+{"name":"run_command","arguments":{"command":"pattern.options","params":{"showSwatchBounds":true}}}
+{"name":"run_command","arguments":{"command":"prefs.set","params":{"key":"patternTileEdgeColor","value":"#ff4f4f"}}}
 ```