feat: lighter air control (steer + stronger strafe) and 2-charge dash

- Air: direct steering bends existing velocity toward input without changing
  its magnitude (air_steer_rate), on top of Quake accelerate with raised
  gains (air_strafe_accel 55->90, per-tick cap 1.2->2.5). No-input air drag
  nearly removed so held momentum carries. Steering skips opposing input to
  avoid flipping through zero.
- Dash: charge system on the machine — dash_charges (2) spend instantly,
  each recharges in dash_cooldown (2 s). get_dash_cooldown_remaining() now
  reports time to the NEXT charge (0 while one is banked) so existing HUDs
  keep working; get_dash_charges() added for pips.
- Tests: dash tests updated to the charge API + new coverage for
  spend-2-then-recharge; 11/11 pass, spawn smoke clean.

Co-Authored-By: Claude Fable 5 <[email protected]>

movement/states/state_air.gd

@@ -45,9 +45,21 @@ func update(delta: float) -> void:
 			# Quake's trick: cap per-tick projection so sharp turns give the gain
 			accel_speed = minf(accel_speed, params.air_wish_speed_cap)
 			hvel += wish_dir * accel_speed
+
+		# Direct steering: bend existing velocity toward the input WITHOUT
+		# changing its magnitude, so airborne direction changes feel light.
+		# Skipped when input opposes travel (braking is the accel path's job,
+		# and lerping through zero would flip the heading unstably).
+		var speed_now := hvel.length()
+		if speed_now > 1.0:
+			var travel_dir := hvel / speed_now
+			if travel_dir.dot(wish_dir) > -0.7:
+				var steered := hvel.lerp(wish_dir * speed_now, params.air_steer_rate * delta)
+				if steered.length_squared() > 0.01:
+					hvel = steered.normalized() * speed_now
 	else:
-		# No input: slight air drag (very subtle)
-		hvel *= (1.0 - 0.5 * delta)
+		# No input: barely any drag — held momentum should carry
+		hvel *= (1.0 - 0.15 * delta)
 
 	vel.x = hvel.x
 	vel.z = hvel.z
@@ -127,6 +139,6 @@ func update(delta: float) -> void:
 				return
 
 	# ── Dash ──────────────────────────────────────────────────────────────
-	if machine.input_dash and machine.dash_cooldown_timer <= 0.0:
+	if machine.input_dash and machine.can_dash():
 		machine.switch_to("dash")
 		return