Implement #77, #78 and #79

#77 - the Distorder becomes the Energy Propulser. Renamed everywhere the
player reads it, reskinned to match: a symmetric hull flaring into an engine
skirt instead of the lopsided warped lump, an engine bell with a thrust plume
instead of the wobbling ring glyph, and energy's own yellow instead of purple,
since energy is what it burns. The internal id stays "distorder" - it is the
capability string, the unlock key and the component scene name, and renaming
the wiring would be a large mechanical change with no player-visible effect.

Its speed ceiling now grows with the LOGARITHM of how many fly. Each one used
to add a flat 1.0, so a fleet that could afford six simply drove at six times
cruise and the vessel stopped being a choice. Base-2 makes the rule one
sentence - every doubling adds another 1.0 - and leaves two propulsers worth
exactly what they were worth before, so nothing already built is devalued.

#78 - a gas burner can be paused. It converts gas the player may want for
bombs into energy they may not need yet, and the only way to stop it was to
demolish it. The action is data-driven like every other: the visual's
ActionProvider lists "pause", and any converter can adopt it. Pause is the
burner's PRIMARY action, so it is one tap rather than a menu; the button shows
what it will DO, bars while running and a play triangle while stopped; and the
building itself goes visibly cold, because a paused building that looked
identical to a running one would be a setting to remember rather than see.
Conversion progress is left where it was rather than reset, so switching off
and on again does not discard a part-finished unit.

#79 - picking something up says so. A "+N" with the resource's own mark rises
and fades where it happened. Built from the SAME glyph the resource tables and
transfer rows use, so a material added to the catalog later cannot end up with
one mark in the HUD and a different one in the world. A pickup a full hold
REFUSES raises nothing.

Two Godot traps cost real time here and are now written down where the next
person will hit them:

  - a `#` comment inside a .tres [resource] block is not a comment. It parses
    as part of the preceding value and silently blanks the property after it.
    One in DistorderVesselDefinition.tres left definition_id empty, which
    surfaced as "<blank> did not resolve its definition" in a test far from
    the edit. The note lives in VesselDefinition.gd now.
  - a global class_name is not reliably resolvable, INCLUDING a script's own
    inside its own static function. ResourcePickupVFX.new() failed to compile
    when reached through a preview scene, taking Rock and the gas vents with
    it. It has no class_name now and constructs itself by path.

Suite 114/114.

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

tests/test_distorder_stacking.gd

@@ -2,13 +2,17 @@ extends SceneTree
 
 # Headless gameplay test: run with
 #   godot --headless -s res://tests/test_distorder_stacking.gd
-# Each space-time distorder vessel PAST THE FIRST raises the fleet's speed
-# ceiling by 1.0, so a second one is worth crewing rather than dead weight.
+# Energy Propulsers raise the fleet's speed ceiling together, so a second one
+# is worth crewing rather than dead weight - but with DIMINISHING returns
+# (#77). Each doubling of them adds 1.0, not each vessel: a flat 1.0 apiece
+# meant a fleet that could afford six simply drove at six times cruise and the
+# vessel stopped being a choice.
 #
 # Covers:
 #   A. one vessel gives the original ceiling, so nothing changed for a fleet
-#      that carries a single distorder
-#   B. each additional vessel adds exactly 1.0
+#      that carries a single propulser
+#   B. the ceiling follows log2 of the count - two vessels are worth exactly
+#      what they were worth before the change, and the growth tapers after
 #   C. the fader's full travel reaches the WIDENED ceiling, not the old one
 #   D. losing a vessel mid-boost pulls the fleet back down to the new
 #      ceiling rather than leaving it faster than its crew can sustain
@@ -53,14 +57,33 @@ func _process(delta: float) -> bool:
 					% [game_state.max_fleet_speed_multiplier, GameState.MAX_FLEET_SPEED_MULTIPLIER])
 			print("1 distorder -> ceiling %.1fx" % game_state.max_fleet_speed_multiplier)
 
-			# --- B. each additional vessel adds 1.0 ----------------------
+			# --- B. the ceiling grows with log2 of the count ---------------
+			var previous_gain: float = 1.0
 			for extra in range(1, 4):
 				fleet.add_ship(GameState.VESSEL_DISTORDER)
-				var expected: float = GameState.MAX_FLEET_SPEED_MULTIPLIER + float(extra)
+				var count: int = extra + 1
+				var expected: float = GameState.MAX_FLEET_SPEED_MULTIPLIER \
+					+ log(float(count)) / log(2.0)
 				if not is_equal_approx(game_state.max_fleet_speed_multiplier, expected):
-					return _fail("%d distorders give a ceiling of %.1f, expected %.1f" \
-						% [extra + 1, game_state.max_fleet_speed_multiplier, expected])
-				print("%d distorders -> ceiling %.1fx" % [extra + 1, game_state.max_fleet_speed_multiplier])
+					return _fail("%d propulsers give a ceiling of %.2f, expected %.2f" \
+						% [count, game_state.max_fleet_speed_multiplier, expected])
+				# Each vessel must be worth strictly less than the one before
+				# it. That is the whole point of the change, and asserting the
+				# formula alone would pass just as happily on a linear one.
+				var gain: float = game_state.max_fleet_speed_multiplier \
+					- (GameState.MAX_FLEET_SPEED_MULTIPLIER + log(float(count - 1)) / log(2.0))
+				if count > 2 and gain >= previous_gain:
+					return _fail("propulser %d added %.2f, no less than the %.2f the one before it added - the returns are not diminishing" \
+						% [count, gain, previous_gain])
+				previous_gain = gain
+				print("%d propulsers -> ceiling %.2fx (this one added %.2f)" \
+					% [count, game_state.max_fleet_speed_multiplier, gain])
+
+			# Two propulsers must still be worth exactly what they were before
+			# the change, or an existing fleet was quietly devalued.
+			if not is_equal_approx(GameState.MAX_FLEET_SPEED_MULTIPLIER + log(2.0) / log(2.0),
+					GameState.MAX_FLEET_SPEED_MULTIPLIER + 1.0):
+				return _fail("two propulsers no longer reach the ceiling they used to")
 
 			# --- C. the fader reaches the widened ceiling ----------------
 			# Dragging the track to its top must mean the CURRENT ceiling, or