Stage 5: bosses that move, attacks that warn, and a second boss

Boss movement is a property of the PHASE, not of the boss -- a fight that
stands still and then starts hunting you is one boss with two phases. Four
modes (STATIC, ORBIT, CHASE, WAYPOINTS) handled generically in
SimWorld._move_boss, so a boss that moves is still data. BossDef.stationary
is gone rather than kept beside the phases: a flag claiming the boss stood
still while a phase walked around would be a second source of truth and the
wrong one, so moves() is derived.

CHASE holds a distance instead of closing, because a boss standing on top of
you is a boss whose bullets cannot be read. Waypoints are fractions of the
arena so one phase works in rooms of different sizes. Every mode is speed
clamped in one place -- ORBIT computes an absolute destination and would
otherwise snap onto its circle on the first tick -- and movement slides
against geometry so a boss cannot walk through the pillars its own arena was
designed around.

The room clamp moved to after movement, where it is finally load-bearing. It
was a no-op while every boss stood still, which is exactly when an invariant
is cheapest to establish: boss rooms deliberately do not lock, so walking out
is always an escape, and that only holds if the boss cannot follow.

TelegraphedStrikeEmitter marks spots and fills them a moment later. The moment
between is the feature: a burst at your feet is a coin flip, the same burst
with a second of notice is a question. It stays stateless like every other
emitter -- they are shared resources and two bosses of the same kind must not
stomp each other -- so strike positions are derived from the volley number and
a test asserts the burst lands where the marker promised. Markers are drawn
through fog and through walls, unlike everything else in the view, because a
warning you cannot see is an unavoidable hit with extra steps.

The Cantor of the Vault fights in the choir vault: static, then a four-corner
circuit, then a chase, then orbiting while marking. It exists to prove the
format stretched, and a test asserts it uses both new mechanisms.

Which boss a run has now comes from its SEED rather than its depth. Depth is a
dev flag nothing in play raises, so the arena was keyed to something no player
can change and the second boss was unreachable in an actual game.

Two things found while finishing:

  - tools/export_content.gd had a hand-maintained boss list and had already
    gone stale, silently not writing the Cantor. Content.ALL_ENEMIES and
    ALL_BOSSES now feed the export tool, the renderer and five tests that each
    kept their own copy.
  - diag_loot failed intermittently after another diagnostic. Taking over from
    the bot cleared its input queue but not its HELD input, so a starved server
    coasted on the bot's last movement vector for half a second and walked the
    player off the item it had been placed on. The press arrived correctly,
    which is why "the press reached the simulation" passed while everything it
    should have caused failed.

check.sh clean, 409 tests, SMOKE PASS (19 assertions), all four diagnostics
green.

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

docs/DECISIONS.md

@@ -362,3 +362,38 @@ old 100000 health was already past the u16 the snapshot sends enemy health in,
 and once a shot did 60 a patient player could have worn it down and left the
 hub without a practice target until the next restart. A flag says what was
 actually meant.
+
+---
+
+## Bosses that move, and attacks that warn
+
+**Movement belongs to the phase, not to the boss.** A fight that stands still
+and then starts hunting you is one boss with two phases. `BossDef.stationary`
+was removed rather than kept alongside the phases: a flag claiming the boss
+stood still while one of its phases walked around would be a second source of
+truth, and the wrong one. `BossDef.moves()` is derived.
+
+**CHASE holds a distance instead of closing.** A boss standing on top of a
+player is a boss whose bullets cannot be read, and this genre cannot afford
+that. It backs off when you come inside its preferred range.
+
+**Waypoints are fractions of the arena.** The Warden's hall and the Choir Vault
+are different sizes, and a phase written against absolute coordinates would only
+work in one of them.
+
+**The boss room clamp moved after movement.** It was a no-op while every boss
+was stationary. Boss rooms deliberately do not lock, so walking out is always an
+escape — which is only true if the boss cannot follow.
+
+**Telegraphed strikes are announced by a stateless emitter.** Emitters are
+shared resources, so nothing may be remembered between the warning and the
+strike; the positions are derived from the volley number instead, and a test
+asserts the burst lands where the marker promised.
+
+**Telegraph markers are drawn through fog and through walls**, unlike every
+other thing in the view. A warning you cannot see is an unavoidable hit with
+extra steps, which is the opposite of what a telegraph is for.
+
+**Which boss a run has comes from its seed, not its depth.** Depth is a dev flag
+that nothing in play raises, so keying the arena to it meant the second boss
+existed and no player could ever reach it.