Lakes fill only to their lower rim and keep clear of spawn and the dock (t96)

The lake lip was Math.min(surfY), the highest ground (y grows downward), so water was poured
above the lower rim and, once levelled, ran up to the trade dock on 4 of 12 seeds. The lip is
now the lower rim edge minus one, and each lake stays 80 grains from spawn. Seed hashes and
the shallow-ore hash re-baselined (changes only under lake basins); golden fixtures also
freeze surfY/dirtY/AMB from the previous generator.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/t_lakes.js

@@ -17,11 +17,14 @@ function surfacePools() {
   })()`);
 }
 for (const [seed, expected] of [
-  [7, '669a4ee87496be27473d2987d9a8935be1a19b29a8f2433d306f32a1616f3bca'],
-  [42, 'efeadd2bff0ce3eaf81e5a08a998ce767e9667e3b27b8623e928f202669f640e'],
-  [424242, '24b5e6ccc4e7d5eb9d54c3ff0fa5dfe84185b83e75b07261ac007b4f920f0640'],
+  [7, '4c4778417e6cf6e9577b831e66111bd374068a14e15642bae304b8a45a68b879'],
+  [42, '907f2ed79b9fda1ae99c5ee55fa19ce85eff8ffdcd7dadac14a2deb42223217d'],
+  [424242, '40080ea6039d0d4247e36fd9a5837d0675100414f198d77419ecf500c7f9d6ad'],
   [2, null],
   [1, null],
+  // Before t96 round 3 these lakes ran over their lower rim up to the trade dock.
+  [5, null],
+  [6, null],
 ]) {
   run(`generateWorld(${seed}, 2048, 1024, (f, label) => {
     if (f === 0.99 && label === 'Finishing') globalThis.waterBeforeLevel = mat.reduce((n, m) => n + (m === WATER), 0);
@@ -33,6 +36,8 @@ for (const [seed, expected] of [
   check(`seed ${seed} conserves water through levelling`, run('mat.reduce((n, m) => n + (m === WATER), 0) === waterBeforeLevel'));
   const initial = surfacePools();
   check(`seed ${seed} starts with flat surface pools`, initial.length > 0 && initial.every(p => p.max - p.min <= 1), JSON.stringify(initial));
+  check(`seed ${seed} keeps its lakes clear of the trade dock`, run(`(() => { const d = machines.find(m => m && m.type === 'dock');
+    return ${JSON.stringify(initial)}.every(p => p.x1 < d.x - 8 || p.x0 > d.x + 24 + 8); })()`), JSON.stringify(initial));
   check(`seed ${seed} restores pinned generation switches`, run('LSTEP === 8 && LFILM === 4 && SORTP === 0.06 && CORNER_SEAL && POWDER_FAN'));
   check(`seed ${seed} starts every water area awake`, run(`mat.every((m, i) => m !== WATER || awake[((i / W) >> 5) * CW + ((i % W) >> 5)] > 0)`));
   check(`seed ${seed} has no submerged tree base`, run('treeBases.every(i => !treeHeld(i) || mat[i] !== WATER)'));