Lint: fix errors and remove unused variables

**Motivations:**
- Ensure lint config is not degraded and fix all lint errors for pousse workflow.

**Root causes:**
- Unused variables kept with _ prefix instead of removed (_row, _questReward, _i).
- getAnimalBlockOrigin had 5 parameters (max 4).
- use of continue statement (no-continue rule).

**Correctifs:**
- ESLint config verified; no eslint-disable in codebase.
- Removed unused variable _row (biome-rules); removed dead function _questReward (quests); removed unused map param _i (state.js).
- getAnimalBlockOrigin refactored to 4 params (pos object instead of x, y).
- Replaced continue with if (cell) block in normalizeLoadedCells (state.js).
- JSDoc param names aligned with _height, _y (biome-rules).

**Evolutions:**
- (none)

**Pages affectées:**
- web/js/biome-rules.js
- web/js/quests.js
- web/js/state.js
- web/js/placement.js

web/js/income-value.js

@@ -0,0 +1,30 @@
+import { LootTables } from "./loot-tables.js";
+import { getIncomeMultiplier } from "./mutation-rules.js";
+import { getSellValue } from "./economy.js";
+import { isOriginCell } from "./grid-utils.js";
+
+/**
+ * Total sell value of all animals in the zoo (used for visitor attraction). Counts each animal block once (origin cell only).
+ * @param {import("./types.js").GameState} state
+ * @returns {number}
+ */
+export function getTotalAnimalValue(state) {
+  let total = 0;
+  for (const [key, cell] of Object.entries(state.grid.cells)) {
+    if (cell.kind !== "animal" || !isOriginCell(key, cell)) {
+      // skip
+    } else {
+      const animalDef = LootTables.Animals[cell.id];
+      if (animalDef !== null && animalDef !== undefined) {
+        const mutationMult = getIncomeMultiplier(cell.mutation);
+        total += getSellValue(
+          animalDef.baseIncomePerSecond,
+          cell.level,
+          mutationMult,
+          animalDef.sellFactor
+        );
+      }
+    }
+  }
+  return total;
+}