#108: the prologue - the convoy, the ambush, and the breach

Landed as one piece across #122, #123 and #124: the frame is useless without
a script, and the script has nowhere to run without the frame.

The director drives the REAL scene rather than being a scene of its own. It
wants the real fleet, the real enemies and the real asteroid field, and it
makes "then the game starts" cost nothing - the director stops steering,
clears the flag, and what is left running is the ordinary game.

The script is a list of beats, each with a deadline as well as its own
completion test, so a beat whose condition is never met - a player who
refuses to fly at the ambush - runs out rather than wedging the prologue.
skip() ends the whole thing at any point and lands in exactly the state
playing it through does, so the game has one way to start rather than two
that have to be kept in step. The test pins that equivalence.

"No action button available, only movements" is enforced where the buttons
are decided, not by the director reaching in: the ability controllers set
their own visibility every frame and would have put them straight back, and
the map button belongs to the map. The joystick, the pivot and the fader
stay.

The convoy is ten hulls where a new game's fleet is one, so it needs an
explicit fleet-size override - a plain number rather than a fake doctrine,
because nothing about the player's own progression should be bent to fit a
cutscene. It is carriers rather than transporters: transporters belong to
hubs and are not fleet-eligible, so a convoy of them would be silently
filtered down to its escorts.

The ambush is chasers and only chasers. "Easy enough" is the requirement,
and a sniper against a convoy the player cannot yet fight properly is
neither easy nor a good first impression.

The breach takes the wheel through one check in GameController, covering the
stick, the keyboard and the released-again path together - three separate
gates would be three chances for one of them to keep steering. The shake is
written to camera.offset, never to its position, because GameController owns
where the camera is and would smooth a shake away.

The vessel that survives is chosen as the interceptor rather than whichever
happened to be first in the list, and the prologue ends on exactly a new
game's opening position.

Also: PlanetAtmosphereController no longer spawns the opening fleet while
the prologue is arming, and the tests that are about what the GAME starts
from now say so by turning the prologue off.

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

tests/test_dev_mode.gd

@@ -36,6 +36,9 @@ func _process(delta: float) -> bool:
 		0:
 			# --- E. a normal game hands over nothing ----------------------
 			game_state.reset_new_game()
+			# #108: reset_new_game() also arms the prologue. Nothing below is
+			# about it, and this test never builds a scene for it to run in.
+			game_state.intro_active = false
 			if game_state.rocks != 0:
 				return _fail("a normal game started with %d ore banked" % game_state.rocks)
 			for resource_type in game_state.resource_types():