telemetry: emit track geometry (DriveGraph nodes) in RaceStarted

Walk the main driveline graph at race start and populate
TrackGeometry with center, left/right edge, width, and
distance_from_start for each DriveNode quad. Includes bounding
box and start position/heading for 2D minimap rendering.

src/network/telemetry/telemetry_emitter.cpp

@@ -19,9 +19,12 @@
 #include "tracks/track.hpp"
 #include "tracks/track_sector.hpp"
 #include "tracks/check_manager.hpp"
+#include "tracks/drive_graph.hpp"
+#include "tracks/drive_node.hpp"
 #include "utils/log.hpp"
 #include "utils/string_utils.hpp"
 
+#include <algorithm>
 #include <chrono>
 #include <cstdlib>
 #include <random>
@@ -176,6 +179,106 @@ void TelemetryEmitter::onRaceStarted()
         }
     }
 
+    // --- Track geometry (for 2D minimap / replay) ---
+    DriveGraph* graph = DriveGraph::get();
+    if (graph != nullptr && graph->getNumNodes() > 0)
+    {
+        auto* geom = ev->mutable_track_geometry();
+
+        float min_x = 1e9f, min_y = 1e9f, min_z = 1e9f;
+        float max_x = -1e9f, max_y = -1e9f, max_z = -1e9f;
+
+        // Walk the main driveline loop following successor 0.
+        unsigned int num_nodes = graph->getNumNodes();
+        unsigned int current = 0;
+        unsigned int visited = 0;
+
+        do {
+            const DriveNode* dn = graph->getNode(current);
+            if (dn == nullptr) break;
+
+            auto* node = geom->add_nodes();
+
+            // Center
+            const Vec3& center = dn->getCenter();
+            auto* c = node->mutable_center();
+            c->set_x(center.x());
+            c->set_y(center.y());
+            c->set_z(center.z());
+
+            // Width
+            node->set_width(dn->getPathWidth());
+
+            // Distance from start
+            node->set_distance_from_start(dn->getDistanceFromStart());
+
+            // Left and right edge points from Quad corners.
+            // Quad layout: [0]=lower-right, [1]=lower-left, [2]=upper-left, [3]=upper-right
+            const Vec3& lr = (*dn)[0];
+            const Vec3& ll = (*dn)[1];
+            const Vec3& ul = (*dn)[2];
+            const Vec3& ur = (*dn)[3];
+
+            // Left edge = midpoint of lower-left and upper-left
+            auto* left = node->mutable_left_edge();
+            left->set_x((ll.x() + ul.x()) * 0.5f);
+            left->set_y((ll.y() + ul.y()) * 0.5f);
+            left->set_z((ll.z() + ul.z()) * 0.5f);
+
+            // Right edge = midpoint of lower-right and upper-right
+            auto* right = node->mutable_right_edge();
+            right->set_x((lr.x() + ur.x()) * 0.5f);
+            right->set_y((lr.y() + ur.y()) * 0.5f);
+            right->set_z((lr.z() + ur.z()) * 0.5f);
+
+            // Update bounding box
+            min_x = std::min(min_x, center.x());
+            min_y = std::min(min_y, center.y());
+            min_z = std::min(min_z, center.z());
+            max_x = std::max(max_x, center.x());
+            max_y = std::max(max_y, center.y());
+            max_z = std::max(max_z, center.z());
+
+            // Follow successor 0 (main driveline)
+            if (dn->getNumberOfSuccessors() > 0)
+                current = dn->getSuccessor(0);
+            else
+                break;
+
+            visited++;
+        } while (current != 0 && visited < num_nodes);
+
+        // Bounding box
+        auto* bmin = geom->mutable_bbox_min();
+        bmin->set_x(min_x);
+        bmin->set_y(min_y);
+        bmin->set_z(min_z);
+        auto* bmax = geom->mutable_bbox_max();
+        bmax->set_x(max_x);
+        bmax->set_y(max_y);
+        bmax->set_z(max_z);
+
+        // Start position + heading
+        const DriveNode* start_node = graph->getNode(0);
+        if (start_node != nullptr)
+        {
+            auto* sp = geom->mutable_start_position();
+            sp->set_x(start_node->getCenter().x());
+            sp->set_y(start_node->getCenter().y());
+            sp->set_z(start_node->getCenter().z());
+
+            // Heading from node 0 toward its successor
+            if (start_node->getNumberOfSuccessors() > 0)
+            {
+                geom->set_start_heading(
+                    start_node->getAngleToSuccessor(0));
+            }
+        }
+
+        Log::info("Telemetry", "Track geometry: %u nodes, bbox=(%.0f,%.0f)-(%.0f,%.0f)",
+                  visited, min_x, min_z, max_x, max_z);
+    }
+
     sendFrame(frame);
     Log::info("Telemetry", "Race started: game_id=%s track=%s karts=%d",
               m_game_id.c_str(), rm->getTrackName().c_str(), num_karts);