fix(ui): keep vitest coverage config out of vite.config.ts

vue-tsc typechecks vite.config.ts, and importing vitest/config's
defineConfig there pulled vitest's transitive vite 6 types into a hard
conflict with the app's vite-5-typed plugins (the pnpm tree resolves
both vite 5 and 6), breaking `pnpm build` and every job that runs it.

Move the coverage block to a dedicated ui/vitest.config.ts, which
tsconfig does not include (so vue-tsc never sees it). vitest auto-loads
it ahead of vite.config.ts and mergeConfig keeps the vue/i18n plugins.
vite.config.ts returns to its pristine, type-clean state. Also ignore
the generated coverage/ report dir in eslint.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WvXMHHbYGddVPpmQR2XmK1

Author: claude

ui/eslint.config.js

@@ -13,6 +13,7 @@ export default [
   {
     ignores: [
       "dist/**",
+      "coverage/**",
       "node_modules/**",
       "src-tauri/**",
       "*.config.js",

ui/vite.config.ts

@@ -1,5 +1,4 @@
-/// <reference types="vitest/config" />
-import { defineConfig } from "vitest/config";
+import { defineConfig } from "vite";
 import vue from "@vitejs/plugin-vue";
 import VueI18nPlugin from "@intlify/unplugin-vue-i18n/vite";
 import path from "node:path";
@@ -19,28 +18,6 @@ export default defineConfig({
     alias: { "@": path.resolve(__dirname, "./src") },
   },
   clearScreen: false,
-  // Vitest config. Per-file `// @vitest-environment jsdom` docblocks still
-  // select jsdom where a test needs the DOM; the default stays node.
-  test: {
-    coverage: {
-      provider: "v8",
-      // `json-summary` feeds the CI coverage-gate (.total.lines.pct); `lcov`
-      // is for local HTML drilldown; `text` prints the table in the run log.
-      reporter: ["text", "json-summary", "lcov"],
-      reportsDirectory: "./coverage",
-      // Count the shipped app code. `all: true` so an untested NEW file lands
-      // as 0%-covered and drags the total DOWN, which is what the coverage
-      // gate (CONTRIBUTING.md) needs to catch a regression.
-      all: true,
-      include: ["src/**/*.{ts,vue}"],
-      exclude: [
-        "src/**/*.d.ts",
-        "src/main.ts",
-        "src/locales/**",
-        "src/**/__tests__/**",
-      ],
-    },
-  },
   server: {
     port: 5173,
     strictPort: true,

ui/vitest.config.ts

@@ -0,0 +1,39 @@
+import { defineConfig, mergeConfig } from "vitest/config";
+import viteConfig from "./vite.config";
+
+// Coverage / test config lives HERE, not in vite.config.ts, on purpose.
+// vue-tsc typechecks vite.config.ts (it is in tsconfig "include") but NOT this
+// file, so putting the `test` block here keeps vitest's vite-6 types from
+// clashing with the app's vite-5-typed plugins - the pnpm tree resolves both
+// vite 5 and vite 6, and importing vitest/config's defineConfig into a
+// typechecked file makes that clash a hard `vue-tsc` error.
+//
+// vitest auto-loads vitest.config.* ahead of vite.config.*; mergeConfig folds
+// in the vue / i18n plugins + alias so component tests keep working. The
+// `// @vitest-environment jsdom` per-file docblocks still select jsdom where a
+// test needs the DOM; the default stays node.
+export default mergeConfig(
+  viteConfig,
+  defineConfig({
+    test: {
+      coverage: {
+        provider: "v8",
+        // `json-summary` feeds the CI coverage gate (.total.lines.pct); `lcov`
+        // is for local HTML drilldown; `text` prints the table in the run log.
+        reporter: ["text", "json-summary", "lcov"],
+        reportsDirectory: "./coverage",
+        // Count the shipped app code. `all: true` so an untested NEW file lands
+        // as 0%-covered and drags the total DOWN, which is what the coverage
+        // gate (CONTRIBUTING.md) needs to catch a regression.
+        all: true,
+        include: ["src/**/*.{ts,vue}"],
+        exclude: [
+          "src/**/*.d.ts",
+          "src/main.ts",
+          "src/locales/**",
+          "src/**/__tests__/**",
+        ],
+      },
+    },
+  }),
+);