Brain graph: thinner ring, integer border, heavier connections

The ring share drops from the wordmark's 0.231 to 0.18 so the disc reads as a
dot at 32px, and both the border and the gap are rounded where they are applied
— a fractional border snaps per edge and left the disc off centre. Connections
and their port dots go up with it, pulse width included, so an arriving message
never draws its edge thinner than it rests.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HTsT1isxUjw5gtkJk8WhuA

frontend/src/components/Flow/flow.css

@@ -20,6 +20,11 @@
   );
   --xy-edge-stroke-selected: var(--primary);
   --xy-edge-stroke-width: 1.5;
+  /*
+   * What a pulse widens to on its way in; the width above is where it settles
+   * back. Per canvas, because the brain draws its connections heavier.
+   */
+  --edge-pulse-width: 2.5;
   --xy-handle-background-color: var(--card);
   --xy-handle-border-color: var(--muted-foreground);
   --xy-selection-background-color: color-mix(
@@ -59,7 +64,7 @@
   @keyframes edge-pulse {
     from {
       stroke: var(--primary);
-      stroke-width: 2.5;
+      stroke-width: var(--edge-pulse-width);
     }
     to {
       stroke: var(--edge-rest);
@@ -137,8 +142,13 @@
 .react-flow.brain-flat {
   --xy-background-color: transparent;
   --brain-decay: 90s;
-  /* Thicker than the editor's, to match the weight the mark draws them at. */
-  --xy-edge-stroke-width: 2;
+  /*
+   * Thicker than the editor's, to match the weight the mark draws them at — and
+   * the pulse widens with it, or a message would leave its edge looking thinner
+   * than it rests.
+   */
+  --xy-edge-stroke-width: 3;
+  --edge-pulse-width: 4;
   --xy-background-pattern-dots-color: color-mix(
     in srgb,
     var(--muted-foreground) 22%,
@@ -296,7 +306,7 @@
 .brain-dot {
   fill: var(--card);
   stroke: var(--brain-ink);
-  stroke-width: 1.5;
+  stroke-width: 2;
 }
 
 .brain-dot.brain-dot-out {