Sharpen upgrades, mark the convoy's destination, and give the world sound

#204 the Beam Collimator widens the beam instead of adding range to one that
already crosses the screen; beam width becomes a per-shot vessel stat.
#205 the Energy Propulser gains three upgrades - dash recharge, dash reach,
and boosted-cruise drain - which turns three constants into vessel stats.
#206 three further doctrines carry the fleet from ten to twenty.
#207 the prologue's World Ship gets a marker, through the scanner's own
guidance arrow rather than a second one.
#208 #210 #213 #214 four new synthesised sounds: the breach opening, cargo
reaching the hold, a rock breaking, and a gas bomb blooming.
#215 building health bars are larger, plated and framed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019AJMdB7iuHuLFZM1aBu3GD

tests/test_laser_vessel.gd

@@ -288,6 +288,41 @@ func _process(delta: float) -> bool:
 				return _fail_now("dragging further did not reach past the nearer enemy")
 			print("drag depth selects between a near and a far target in the same cone")
 
+			# --- G. #204: the Collimator widens what one shot catches -------
+			# The upgrade used to add range to a beam that already crossed the
+			# screen; it adds WIDTH now, so this checks the thing it widens is
+			# the hit test and not only the picture.
+			for placed in [near_enemy, far_enemy, out_of_cone]:
+				if is_instance_valid(placed):
+					placed.free()
+			var laser: Node = first_shooter.get_component("laser")
+			var narrow_width: float = laser.beam_half_width
+			game_state.vessel_levels["lsr_width"] = 3
+			laser.apply_stats()
+			if not is_equal_approx(laser.beam_half_width, narrow_width + 66.0):
+				return _fail_now("three Collimators gave a half-width of %.0f, expected %.0f" \
+					% [laser.beam_half_width, narrow_width + 66.0])
+
+			# Off the line by more than the base beam covers and less than the
+			# researched one does, so the same shot answers differently.
+			var flanker: Node = load("res://enemies/Enemy.tscn").instantiate()
+			flanker.position = first_shooter.global_position \
+				+ Vector2(600.0, narrow_width + 60.0)
+			main.add_child(flanker)
+			flanker.speed = 0.0
+			var beam_script: Resource = load("res://vfx/LaserBeamEffect.gd")
+			var narrow_shot: Node2D = beam_script.fire(root, first_shooter.global_position,
+				Vector2.RIGHT, 2900.0, 1, narrow_width)
+			if narrow_shot.hit_count != 0:
+				return _fail_now("the unresearched beam already reached the flanking enemy")
+			var wide_shot: Node2D = beam_script.fire(root, first_shooter.global_position,
+				Vector2.RIGHT, 2900.0, 1, laser.beam_half_width)
+			if wide_shot.hit_count != 1:
+				return _fail_now("the widened beam hit %d enemies, expected the flanker" \
+					% wide_shot.hit_count)
+			print("Beam Collimator: %.0f -> %.0f half-width, and the wider beam catches what the narrow one missed" \
+				% [narrow_width, laser.beam_half_width])
+
 			print("TEST_LASER_VESSEL: PASS")
 			quit(0)
 			return true