[visual-qa] Drawing a second CircularString streams extra points: arc cuts off, leftover chord

[grootstebozewolf]

Observed

UX on TestBuilder RC1. CircularString draw tool.

First: CIRCULARSTRING (6 73, 51 75, 80 15).
Then a second intersecting arc. Intended third click POINT (46 91).

Got:

MULTICURVE (
  CIRCULARSTRING (6 73, 51 75, 80 15),
  CIRCULARSTRING (38 27, 35 71, 35.4 72.6))

The second arc is cut off near the second control (35 71 → 35.4 72.6). The line toward (46 91) shows as a chord, not a circle-segment preview.

Expected

• Click-only control points. Drag must not stream extra CircularString vertices (that is LineString stream-draw).
• Second component: CIRCULARSTRING (38 27, 35 71, 46 91) — full arc through the clicked third point.
• In-progress preview of a complete (start, mid, mouse) triple is an arc, not a leftover chord.
• Combining intersecting CircularStrings must not clip them.

Cause (code)

CircularStringTool extends AbstractStreamDrawTool. mouseLocationChanged adds coordinates while BUTTON1 is down. A slight drag after the second click inserts (35.4 72.6), completes a 3-point string prematurely, and the real third click becomes an even leftover (chord preview; dropped on bandFinished).

Not

• Not EditVertex even-count insert ([visual-qa] EditVertex right-click add vertex on CIRCULARSTRING makes even control count #82).
• Not 3-click CurvePolygon complementary mid ([visual-qa] 3-click CurvePolygon circle is CIRCULARSTRING(A,B,C,A) but draws a closing line #86).

[grootstebozewolf]

PR #93: CircularString/CompoundCurve/CurvePolygon draw no longer stream-add on drag. The second intersecting arc's third click stays the arc end (46 91), not a leftover chord after a drag ghost (35.4 72.6).

Needs UX SIGN before close.