t_p1_round: Add round/match lifecycle system (RoundManager)

- New server/scripts/round/round_manager.gd with:
  - RoundPhase enum (WARMUP, PREP, LIVE, POST)
  - Round life cycle: warmup -> prep (15s) -> live (105s) -> post (8s)
  - Team elimination detection using entity->peer->team mappings
  - Time-expired round ending (default: CT wins)
  - Economy hooks: win money (250), loss money (900 escalating to 900), kill bonus (00)
  - All requested signals: round_phase_changed, round_started, round_ended, match_point, warmup_ended, round_economy_data

- Updated GameServer:
  - Creates and wires RoundManager in _ready()
  - Connects DamageProcessor.player_killed -> round tracking + elimination detection
  - Added peer_to_entity mapping for backwards entity lookup
  - Added RCON command handler (_on_rcon_command) for start_match/end_round

- Updated RCON command handler:
  - Added start_match and end_round to dispatch list and help text

client/assets/scenes/modular/pieces/barrel.tscn

@@ -0,0 +1,16 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.7, 0.15, 0.1, 1.0)
+roughness = 0.6
+metallic = 0.2
+resource_name = "red_barrel"
+
+[node name="Barrel" type="CSGCylinder3D"]
+radius = 0.6
+height = 1.0
+material = SubResource("1")
+use_collision = true
+slices = 16
+visibility_range_end = 30.0
+visibility_range_end_margin = 3.0

client/assets/scenes/modular/pieces/corner_wall.tscn

@@ -0,0 +1,26 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.35, 0.4, 0.5, 1.0)
+roughness = 0.8
+metallic = 0.0
+resource_name = "bluegrey_corner"
+
+[node name="CornerWall" type="CSGCombiner3D"]
+use_collision = false
+visibility_range_end = 50.0
+visibility_range_end_margin = 5.0
+
+[node name="WallA" type="CSGBox3D" parent="CornerWall"]
+operation = 0
+size = Vector3(2, 3, 0.2)
+material = SubResource("1")
+use_collision = true
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0.1)
+
+[node name="WallB" type="CSGBox3D" parent="CornerWall"]
+operation = 0
+size = Vector3(0.2, 3, 2)
+material = SubResource("1")
+use_collision = true
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0.1, 0, 0)

client/assets/scenes/modular/pieces/cover_wall.tscn

@@ -0,0 +1,14 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.4, 0.4, 0.4, 1.0)
+roughness = 0.8
+metallic = 0.0
+resource_name = "grey_cover"
+
+[node name="CoverWall" type="CSGBox3D"]
+size = Vector3(2, 1.3, 0.2)
+material = SubResource("1")
+use_collision = true
+visibility_range_end = 40.0
+visibility_range_end_margin = 5.0

client/assets/scenes/modular/pieces/crate.tscn

@@ -0,0 +1,14 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.55, 0.35, 0.15, 1.0)
+roughness = 0.85
+metallic = 0.0
+resource_name = "brown_crate"
+
+[node name="Crate" type="CSGBox3D"]
+size = Vector3(1, 1, 1)
+material = SubResource("1")
+use_collision = true
+visibility_range_end = 40.0
+visibility_range_end_margin = 5.0

client/assets/scenes/modular/pieces/floor_tile.tscn

@@ -0,0 +1,14 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.5, 0.5, 0.5, 1.0)
+roughness = 0.8
+metallic = 0.0
+resource_name = "concrete_grey"
+
+[node name="FloorTile" type="CSGBox3D"]
+size = Vector3(2, 0.2, 2)
+material = SubResource("1")
+use_collision = true
+visibility_range_end = 60.0
+visibility_range_end_margin = 10.0

client/assets/scenes/modular/pieces/pillar.tscn

@@ -0,0 +1,14 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.2, 0.2, 0.22, 1.0)
+roughness = 0.8
+metallic = 0.0
+resource_name = "darkgrey_pillar"
+
+[node name="Pillar" type="CSGBox3D"]
+size = Vector3(0.3, 3, 0.3)
+material = SubResource("1")
+use_collision = true
+visibility_range_end = 30.0
+visibility_range_end_margin = 3.0

client/assets/scenes/modular/pieces/ramp.tscn

@@ -0,0 +1,14 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.7, 0.7, 0.3, 1.0)
+roughness = 0.8
+metallic = 0.0
+resource_name = "yellow_ramp"
+
+[node name="Ramp" type="CSGPolygon3D"]
+polygon = PackedVector2Array(0, 0, 2, 0, 2, 1.155)
+depth = 2.0
+material = SubResource("1")
+use_collision = true
+smooth_faces = true

client/assets/scenes/modular/pieces/stairs.tscn

@@ -0,0 +1,33 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.45, 0.45, 0.45, 1.0)
+roughness = 0.8
+metallic = 0.0
+resource_name = "grey_stairs"
+
+[node name="Stairs" type="CSGCombiner3D"]
+use_collision = false
+visibility_range_end = 40.0
+visibility_range_end_margin = 5.0
+
+[node name="Step1" type="CSGBox3D" parent="Stairs"]
+operation = 0
+size = Vector3(2, 0.25, 0.5)
+material = SubResource("1")
+use_collision = true
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0.125, 0.75)
+
+[node name="Step2" type="CSGBox3D" parent="Stairs"]
+operation = 0
+size = Vector3(2, 0.25, 0.5)
+material = SubResource("1")
+use_collision = true
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0.375, 0.25)
+
+[node name="Step3" type="CSGBox3D" parent="Stairs"]
+operation = 0
+size = Vector3(2, 0.25, 0.5)
+material = SubResource("1")
+use_collision = true
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0.625, -0.25)

client/assets/scenes/modular/pieces/wall_segment.tscn

@@ -0,0 +1,14 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.35, 0.4, 0.5, 1.0)
+roughness = 0.8
+metallic = 0.0
+resource_name = "bluegrey_wall"
+
+[node name="WallSegment" type="CSGBox3D"]
+size = Vector3(4, 3, 0.2)
+material = SubResource("1")
+use_collision = true
+visibility_range_end = 50.0
+visibility_range_end_margin = 5.0

client/assets/scenes/modular/pieces/window_frame.tscn

@@ -0,0 +1,24 @@
+[gd_scene load_steps=2 format=3]
+
+[sub_resource type="StandardMaterial3D" id="1"]
+albedo_color = Color(0.35, 0.4, 0.5, 1.0)
+roughness = 0.8
+metallic = 0.0
+resource_name = "bluegrey_window"
+
+[node name="WindowFrame" type="CSGCombiner3D"]
+use_collision = false
+visibility_range_end = 40.0
+visibility_range_end_margin = 5.0
+
+[node name="MainWall" type="CSGBox3D" parent="WindowFrame"]
+operation = 0
+size = Vector3(4, 3, 0.2)
+material = SubResource("1")
+use_collision = true
+
+[node name="WindowCutout" type="CSGBox3D" parent="WindowFrame"]
+operation = 1
+size = Vector3(2, 2, 0.25)
+use_collision = true
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0)