fix(botapi): static event queue storage + end-of-battle train wait

The event queue's heap seq was the last GC'd block surviving across
rounds: each round runs on a freshly spawned bot thread, so the N+1
thread realloc'd a block grown by dead thread N's allocator mid-round
(at the next capacity doubling, ~turn 104) -> rawDealloc SIGSEGV in
addEvent (7 gdb-confirmed coredumps). Replace with a static
array[MAX_QUEUE_SIZE, BotEvent] + eventsLen: no heap block crosses
threads, realloc can never happen.

Also fix the harness aborting the final round mid-train: PPO_Bot's
onRoundEnded trains synchronously after the runner's RoundEndedEvent,
so the counter read right after awaitResults() is the stale pre-train
value and System.exit killed the bot inside ppoUpdate. Poll up to 60s
for the counter to catch up before declaring the battle incomplete.

Verified: 72 consecutive rounds vs Fire, 100% wins, all rounds trained
(counter advanced 1:1), zero coredumps since the fix.

libs/tankroyale_botapi/tankroyale_botapi/graphics.nim

@@ -0,0 +1,92 @@
+## SVG debug graphics API for Robocode Tank Royale Nim bot API.
+## Module-level procs write SVG into a buffer that is flushed into
+## BotIntent.debugGraphics each tick and cleared afterward.
+
+import std/strformat
+import ./color
+
+# ---------------------------------------------------------------------------
+# Module-level state (single bot per process)
+# ---------------------------------------------------------------------------
+
+var gSvgBuffer:   string
+var gStrokeColor: Color = WHITE
+var gFillColor:   Color = WHITE
+var gStrokeWidth: float = 1.0
+var gFontFamily:  string = "Arial"
+var gFontSize:    float = 12.0
+
+# ---------------------------------------------------------------------------
+# Internal helpers
+# ---------------------------------------------------------------------------
+
+proc svgAttrs(): string =
+  ## Current stroke/fill/width as SVG attribute string.
+  &"stroke=\"{gStrokeColor.toHex}\" fill=\"{gFillColor.toHex}\" stroke-width=\"{gStrokeWidth}\""
+
+proc svgOutput*(): string =
+  ## Returns the SVG fragment for this tick, or "" if nothing was drawn.
+  if gSvgBuffer.len == 0: return ""
+  "<g>" & gSvgBuffer & "</g>"
+
+proc clearGraphics*() =
+  ## Reset buffer and all style globals to defaults. Called after each tick.
+  gSvgBuffer   = ""
+  gStrokeColor = WHITE
+  gFillColor   = WHITE
+  gStrokeWidth = 1.0
+  gFontFamily  = "Arial"
+  gFontSize    = 12.0
+
+# ---------------------------------------------------------------------------
+# State setters
+# ---------------------------------------------------------------------------
+
+proc setStrokeColor*(c: Color) = gStrokeColor = c
+proc setFillColor*(c: Color)   = gFillColor   = c
+proc setStrokeWidth*(w: float) = gStrokeWidth = w
+proc setFont*(family: string; size: float) =
+  gFontFamily = family
+  gFontSize   = size
+
+# ---------------------------------------------------------------------------
+# Draw procs — append raw SVG elements
+# ---------------------------------------------------------------------------
+
+proc drawLine*(x1, y1, x2, y2: float) =
+  gSvgBuffer.add &"<line x1=\"{x1}\" y1=\"{y1}\" x2=\"{x2}\" y2=\"{y2}\" {svgAttrs()}/>"
+
+proc drawRectangle*(x, y, w, h: float) =
+  let attrs = &"stroke=\"{gStrokeColor.toHex}\" fill=\"none\" stroke-width=\"{gStrokeWidth}\""
+  gSvgBuffer.add &"<rect x=\"{x}\" y=\"{y}\" width=\"{w}\" height=\"{h}\" {attrs}/>"
+
+proc fillRectangle*(x, y, w, h: float) =
+  let attrs = &"stroke=\"none\" fill=\"{gFillColor.toHex}\""
+  gSvgBuffer.add &"<rect x=\"{x}\" y=\"{y}\" width=\"{w}\" height=\"{h}\" {attrs}/>"
+
+proc drawCircle*(x, y, r: float) =
+  let attrs = &"stroke=\"{gStrokeColor.toHex}\" fill=\"none\" stroke-width=\"{gStrokeWidth}\""
+  gSvgBuffer.add &"<circle cx=\"{x}\" cy=\"{y}\" r=\"{r}\" {attrs}/>"
+
+proc fillCircle*(x, y, r: float) =
+  let attrs = &"stroke=\"none\" fill=\"{gFillColor.toHex}\""
+  gSvgBuffer.add &"<circle cx=\"{x}\" cy=\"{y}\" r=\"{r}\" {attrs}/>"
+
+proc drawText*(text: string; x, y: float) =
+  gSvgBuffer.add &"<text x=\"{x}\" y=\"{y}\" font-family=\"{gFontFamily}\" font-size=\"{gFontSize}\">{text}</text>"
+
+proc drawPolygon*(points: seq[(float, float)]) =
+  var pts = ""
+  for (px, py) in points:
+    if pts.len > 0: pts.add ' '
+    pts.add &"{px},{py}"
+  let attrs = &"stroke=\"{gStrokeColor.toHex}\" fill=\"none\" stroke-width=\"{gStrokeWidth}\""
+  gSvgBuffer.add &"<polygon points=\"{pts}\" {attrs}/>"
+
+proc fillPolygon*(points: seq[(float, float)]) =
+  var pts = ""
+  for (px, py) in points:
+    if pts.len > 0: pts.add ' '
+    pts.add &"{px},{py}"
+  let attrs = &"stroke=\"none\" fill=\"{gFillColor.toHex}\""
+  gSvgBuffer.add &"<polygon points=\"{pts}\" {attrs}/>"