chore: drop brand names and orphaned PICK_HIGHLIGHT colours

Neutralise vendor references in comments to plain behavioural descriptions
(object acquisition / object snap). Remove the PICK_HIGHLIGHT and
PICK_HIGHLIGHT_DIM wire colours: their only consumer was the stripped
storm-sewer add-on, and the retained plugin acquisition pathway draws the
ObjectPick snap glyph and per-command hover previews instead, so the
constants are dead.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/snap/mod.rs

@@ -31,7 +31,7 @@ pub enum SnapType {
     ApparentIntersection,
     Parallel,
     Grid,
-    /// C3D-style object acquisition (storm structure / network pick) — orange marker.
+    /// Object acquisition (domain-object pick, e.g. network structure) — orange marker.
     ObjectPick,
 }