feat: NTE gear optimizer web app

Client-side optimizer for Neverness to Everness console builds. Imports a
gear export from nte-history-exporter, keeps it in IndexedDB, and solves for
the best module placement per character or across a team.

- domain/: pure ports of the Python research scripts (shapes, cartridges,
  board tiling, stats, scoring, set bonuses, Arc effects, sheet prediction).
  No DOM, no storage imports, so they stay worker-safe and Node-testable.
- solver/: single-character solve with branch and bound, plus a three-phase
  team solve (portfolio, leximin, column generation) over disjoint item sets.
  Runs in a Worker when one can be constructed, inline otherwise.
- db/: three storage tiers selected by use rather than feature detection,
  fail-closed import validation, and undo that restores both sides of a steal.
- ui/: React 19 views for items, characters and teams; the board is drawn as
  the deliverable rather than a score.
- Two build targets: a hosted bundle and a single self-contained nte.html
  with no external requests.

Values the model cannot measure are reported as unavailable rather than
guessed: cartridge set bonuses, the level 80 base-stat multiplier, and the
distinction between "optimal for this packing" and globally optimal.

145 tests, tsc clean, both build targets clean.

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

tests/stats.test.ts

@@ -0,0 +1,94 @@
+import { readFileSync } from "node:fs";
+import { describe, expect, it } from "vitest";
+
+import {
+  BASE_CRIT_DAMAGE,
+  BASE_CRIT_RATE,
+  MULTIPLIER,
+  baseStat,
+  consoleTrait,
+  hasMultiplier,
+  totalAtk,
+  traitContribution,
+} from "../src/domain/stats.ts";
+
+const gamedata = JSON.parse(readFileSync("src/generated/gamedata.json", "utf8"));
+const esperByName = (name: string) =>
+  gamedata.espers.find((esper: { name: string }) => esper.name === name);
+const curve = (esper: { stats: { id_stats: string; values: number[] }[] }, id: string) =>
+  esper.stats.find((stat) => stat.id_stats === id)!.values;
+
+describe("base stats", () => {
+  it("reproduces the measured level-50 HP for two different espers", () => {
+    // Both must come out exact: the five-decimal multiplier floors Adler one
+    // point low, which is what forced the band.
+    // The multiplier is a property of the level, not the character: these two
+    // agree to five decimals while their flat deltas differ by 120.
+    expect(baseStat(curve(esperByName("Haniel"), "HPMaxBase"), 50, "HP")).toBe(8272);
+    expect(baseStat(curve(esperByName("Adler"), "HPMaxBase"), 50, "HP")).toBe(8638);
+  });
+
+  it("reproduces Zankou's measured level-70 sheet", () => {
+    const zankou = esperByName("Zankou");
+    expect(baseStat(curve(zankou, "HPMaxBase"), 70, "HP")).toBe(13466);
+    expect(baseStat(curve(zankou, "DefBase"), 70, "DEF")).toBe(789);
+  });
+
+  it("keeps ATK on a lower multiplier than HP and DEF", () => {
+    // The level-50 bands do not overlap, so the split is real, not rounding.
+    const atk = MULTIPLIER[50]!.ATK as { min: number; max: number };
+    const hp = MULTIPLIER[50]!.HP as { min: number; max: number };
+    expect(atk.max).toBeLessThan(hp.min);
+  });
+
+  it("reports level 80 as unmeasured rather than guessing", () => {
+    expect(hasMultiplier(80)).toBe(false);
+    expect(baseStat(curve(esperByName("Zankou"), "HPMaxBase"), 80, "HP")).toBeNull();
+  });
+});
+
+describe("ATK formula", () => {
+  it("scales the Arc's ATK with ATK% but not flat gear ATK", () => {
+    expect(Math.floor(totalAtk(577, 570, 420, 0.125))).toBe(1710);
+  });
+});
+
+describe("console trait", () => {
+  it("is read from the data, not hardcoded", () => {
+    const zankou = consoleTrait(esperByName("Zankou"))!;
+    expect(zankou).toEqual({
+      stat: "CritDamageBase",
+      name: "CRIT DMG",
+      per: 0.16,
+      moduleCells: 3,
+    });
+  });
+
+  it("is not always CRIT DMG and not always Type III", () => {
+    const traits = gamedata.espers.map((esper: never) => consoleTrait(esper)!);
+    const typeTwo = traits.filter((trait: { moduleCells: number }) => trait.moduleCells === 2);
+    expect(typeTwo).toHaveLength(3);
+    expect(new Set(traits.map((trait: { stat: string }) => trait.stat)).size).toBe(8);
+  });
+
+  it("counts only modules of the trait's own cell count", () => {
+    const zankou = consoleTrait(esperByName("Zankou"))!;
+    // Four Type III modules is the reading Zankou's sheet was solved against:
+    // 0.50 base + 0.60 cartridge main + 0.26 substats + 4 x 0.16 = 2.00.
+    const contribution = traitContribution(zankou, [
+      "cell3_style1",
+      "cell3_style2",
+      "cell3_style3",
+      "cell3_style4",
+      "cell2_style1",
+      "cell4_style1",
+    ])!;
+    expect(contribution.value).toBeCloseTo(0.64, 10);
+    expect(BASE_CRIT_DAMAGE + 0.6 + 0.26 + contribution.value).toBeCloseTo(2.0, 10);
+  });
+
+  it("starts every character at 5% CRIT Rate and 50% CRIT DMG", () => {
+    expect(BASE_CRIT_RATE).toBe(0.05);
+    expect(BASE_CRIT_DAMAGE).toBe(0.5);
+  });
+});