Radial: drop Cut/Copy/Paste now that chords cover them

With left+middle = Cut and left+right = Paste (standard KDE clipboard) and
X11 primary selection for copy, those actions are redundant in the radial
and duplicate a more in-flow gesture. Top-level radial is now Undo, Redo,
Cursors to Line Ends, and More. All 5 ctest suites green.

docs/PLAN.md

@@ -136,6 +136,8 @@ Therefore the palette is replaced, not extended, and the replacement is built on
 - The right-button paste chord is free of conflict because the radial gesture is
   already suppressed while the left button is held: right alone = radial, right
   while left-held = paste.
+- Cut/Copy/Paste were removed from the radial once the chords covered them —
+  the radial should not duplicate what a more in-flow gesture already does.
 - **Middle-click primary paste is suppressed** inside the editor — the middle
   button is consumed on both press and release (the paste fires on release, so
   swallowing only the press leaked it). Paste in the editor is the KDE-clipboard

src/radial/radialconfig.cpp

@@ -114,9 +114,9 @@ QList<RadialDef> RadialConfig::builtinDefault()
     };
 
     edit.root.children = {
-        leaf(QStringLiteral("Cut"), QStringLiteral("edit_cut")),
-        leaf(QStringLiteral("Copy"), QStringLiteral("edit_copy")),
-        leaf(QStringLiteral("Paste"), QStringLiteral("edit_paste")),
+        // Cut/Copy/Paste are intentionally absent: cut and paste are handled by
+        // the Acme left+middle / left+right chords (standard KDE clipboard), and
+        // copy by the X11 primary selection — all more in-flow than a radial trip.
         leaf(QStringLiteral("Undo"), QStringLiteral("edit_undo")),
         leaf(QStringLiteral("Redo"), QStringLiteral("edit_redo")),
         // Multi-cursor on every selected line: a quintessential in-place action