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>

vite.single.config.ts

@@ -0,0 +1,98 @@
+/**
+ * The `file://` build: one HTML file, everything inlined.
+ *
+ * Chrome gives a `file://` document an opaque origin, which costs it IndexedDB,
+ * workers, `fetch` and module scripts. So this build is a classic IIFE with the
+ * game data inlined rather than dynamically imported, and the worker aliased out
+ * entirely. The app degrades behind `PersistenceAdapter` and `SolverHost` and
+ * never sees the difference.
+ */
+import { readFileSync, writeFileSync, rmSync, readdirSync } from "node:fs";
+import { join } from "node:path";
+
+import { fileURLToPath } from "node:url";
+
+import { defineConfig, type Plugin } from "vite";
+import react from "@vitejs/plugin-react";
+
+const fromRoot = (relative: string): string =>
+  fileURLToPath(new URL(relative, import.meta.url));
+
+const OUT_DIR = "dist/single";
+const TARGET = "dist/nte.html";
+
+/** Fold the emitted script and stylesheet into one document. */
+function inlineEverything(): Plugin {
+  return {
+    name: "inline-everything",
+    writeBundle() {
+      const files = readdirSync(OUT_DIR, { recursive: true }) as string[];
+      const scripts = files.filter((name) => name.endsWith(".js"));
+      const styles = files.filter((name) => name.endsWith(".css"));
+      if (scripts.length !== 1) {
+        // More than one chunk means something escaped `inlineDynamicImports`,
+        // and a file:// page cannot fetch the second one.
+        throw new Error(`expected one script, got ${scripts.length}: ${scripts.join(", ")}`);
+      }
+      const script = readFileSync(join(OUT_DIR, scripts[0]!), "utf8");
+      const css = styles.map((name) => readFileSync(join(OUT_DIR, name), "utf8")).join("\n");
+
+      const html = `<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>NTE gear optimizer</title>
+    <style>${css}</style>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script>${script}</script>
+  </body>
+</html>
+`;
+      writeFileSync(TARGET, html);
+      rmSync(OUT_DIR, { recursive: true, force: true });
+      const kb = (html.length / 1024).toFixed(0);
+      // eslint-disable-next-line no-console
+      console.log(`${TARGET}  ${kb} KB, one file, no external requests`);
+    },
+  };
+}
+
+export default defineConfig({
+  base: "./",
+  plugins: [react(), inlineEverything()],
+  resolve: {
+    // Matched against the whole import specifier and replaced with an absolute
+    // path: a regex that rewrites only part of a relative specifier resolves
+    // against the importer's directory and lands nowhere.
+    alias: [
+      {
+        find: /^\.\/worker-host\.ts$/,
+        replacement: fromRoot("src/solver/worker-host.single.ts"),
+      },
+      {
+        // No artwork travels with the single file, so the manifest is emptied
+        // rather than left to request images that are not there.
+        find: /^\.\.\/generated\/icons\.json$/,
+        replacement: fromRoot("src/generated/icons.empty.json"),
+      },
+    ],
+  },
+  build: {
+    outDir: OUT_DIR,
+    emptyOutDir: true,
+    target: "es2022",
+    cssCodeSplit: false,
+    assetsInlineLimit: Number.MAX_SAFE_INTEGER,
+    rollupOptions: {
+      output: {
+        format: "iife",
+        inlineDynamicImports: true,
+        entryFileNames: "app.js",
+        assetFileNames: "app.[ext]",
+      },
+    },
+  },
+});