feat(levels): assemble the 50-level campaign and the sheet to review it

The deep-lock construction cannot go below three turns, so it cannot supply an
opening band — every level it makes lands mid-difficulty and the curve comes
out flat. harvest-easy pulls the shallow end from the shipped v0.5 set, but
only the 3% of it that holds up: 568 of 1000 need no rotation at all and 51
more are clearable by tapping at random, which is what the monkey threshold is
for. 33 levels survive, at one and two turns.

select-50 scores candidates on mechanical features only, spreads the pick
evenly across that range, and caps any one route grammar at 36% so the campaign
cannot quietly become one template repeated — the shipped 1000 turned out to be
thirty. Weights are a flag, so refitting them from a round of agent ratings is
a re-run rather than an edit.

The result is a curve rather than a plateau: difficulty score 3.85 / 6.24 /
7.60 across the three bands, rotations 1.8 / 3.0 / 3.5, and every level keeps
three or more opening choices with a show of at least a second.

The 50 register as a playable campaign edition, so review happens in the real
game; docs/review-50.html is the handover sheet, one card per level with the
opening position drawn from the solver rather than sketched.

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

src/showcase.js

@@ -4,12 +4,11 @@ import { itemStudy } from './item-study.js';
 import { attachBoardViewport } from './board-viewport.js';
 import { createStudyLevel } from './study-levels.js';
 import { TapQueue } from './tap-queue.js';
-import { exitTiming } from './exit-animation.js';
 import { LEVEL_THEMES, PIGMENTS, MOTION, themeWithColors } from './design-tokens.js';
 import { LEVELS } from './levels.js';
 import { Game, available, solveRotations, trace } from './core.js';
 import { layout, hitCell } from './geometry.js';
-import { CanvasPainter, drawScene, drawTile } from './renderer.js';
+import { CanvasPainter, drawScene, drawTile, exitDuration } from './renderer.js';
 import { ICONS, ICON_SIZE, ICON_ATLAS } from './ui-skin.js';
 import { TILE_ATLAS } from './sprites.js';
 const taps=new TapQueue();
@@ -74,7 +73,7 @@ function draw(now=performance.now()){
 function reset(){taps.clear();animation=null;rotation=null;afterRotation=null;hint=null;cancelAnimationFrame(frame);game=new Game(studyLevel);$('phone-status').textContent='点击棋子，沿轨道出发';$('motion-status').textContent='可反复播放，也可直接操作棋盘。';controls();draw();}
 function move(tile){if(animation||rotation){if(taps.add(tile.id,animation?.route.tile.id))draw();return;}hint=null;const route=game.tap(tile.id);if(!['exit','blocked','loop'].includes(route.status))return;
   if(route.status!=='exit')taps.clear();
-  const base=route.status==='exit'?exitTiming(route).duration:MOTION.collisionMs;
+  const base=route.status==='exit'?exitDuration(route,theme.artStyle):MOTION.collisionMs;
   animation={route,start:performance.now(),duration:reduced?150:base*($('slow').checked?2.5:1)};
   $('phone-status').textContent=route.status==='exit'?'沿着轨道，找到出口…':'接触后沿原路返回';$('motion-status').textContent=route.status==='exit'?'正在播放：滑行 → 出口收束 → 六角余韵':'正在展示碰撞反馈';controls();draw();
 }