fix(spatial): decorrelate spawn radius from angle to stop avatar overlap

The previous spawn fix (radius 20 -> 6) traded one problem for another:
hashing only the angle onto a small fixed-radius ring means two names
whose hashes land near the same angle bucket (only 360 of them) now
separate by just a few pixels of arc instead of dozens, since arc
length scales with radius. Confirmed against the actual guest names
from a live session (guest-pxj6/guest-rd7o): old algorithm placed them
~11 room units apart, easily close enough for their ~34px graph nodes
to visually merge into what looked like a single dot.

Now the radius is hashed independently from the angle (8-19 units), so
an angle collision no longer implies a full positional overlap. Same
test names now land ~27.6 units apart. Still well within the range
that keeps audio at full gain (refDistance=4).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

public/app.js

@@ -1524,17 +1524,27 @@ setInterval(() => {
   }
 }, 5000);
 
-// Spawn me slightly off-center so two people don't land exactly on top of
-// each other — small radius on purpose: at refDistance=4/rolloffFactor=1.4,
-// the old radius-20 ring put name-hash-unlucky pairs up to 40 units apart
-// (diametrically opposite), which is already down to ~7% audio gain before
-// anyone's said a word.
+// Spawn me slightly off-center so people don't land on top of each other.
+// A single hashed angle on a *fixed* radius ring (the previous approach)
+// puts anyone whose name hashes to a nearby angle almost exactly on top of
+// each other too — on a small ring, "nearby angle" is only a few pixels of
+// arc, and with just 360 angle buckets that's common (especially with the
+// same recurring guest-xxxx test names). Hashing the radius independently
+// from the angle means an angle collision no longer implies a full overlap.
+// Both stay small enough that at refDistance=4/rolloffFactor=1.4 (see
+// updatePanner) nobody starts out attenuated — this is purely about the
+// dots being visually distinguishable, not audio range.
 (() => {
-  let h = 0;
-  for (const c of S.myId || S.name) h = (h * 33 + c.charCodeAt(0)) >>> 0;
-  const a = (h % 360) * (Math.PI / 180);
-  S.me.x = 50 + 6 * Math.cos(a);
-  S.me.y = 50 + 6 * Math.sin(a);
+  const key = S.myId || S.name;
+  let hAngle = 0, hRadius = 0;
+  for (const c of key) {
+    hAngle = (hAngle * 33 + c.charCodeAt(0)) >>> 0;
+    hRadius = (hRadius * 17 + c.charCodeAt(0) + 7) >>> 0;
+  }
+  const a = (hAngle % 360) * (Math.PI / 180);
+  const r = 8 + (hRadius % 12); // 8..19 room units
+  S.me.x = 50 + r * Math.cos(a);
+  S.me.y = 50 + r * Math.sin(a);
 })();
 
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