fix(web): repair nix frontend build

Two things broke `nix build .#webFrontend`, and with it `nh home apply`
on any host that installs maestro.

`marked` was added to web/package.json without repinning pnpmDeps.hash,
so pnpm install failed offline with ERR_PNPM_NO_OFFLINE_TARBALL.

`tsc -b` also type-checks web/src/toolIcon.test.ts, which imports the
shared ../../fixtures/command-resolution.json. The derivation's src is
./web, so that path does not exist in the sandbox. The production build
now uses tsconfig.build.json, which excludes tests; `pnpm typecheck`
still covers them from a full checkout.

flake.nix

@@ -148,7 +148,7 @@
             pnpmDeps = (pkgs.fetchPnpmDeps.override { pnpm = pkgs.pnpm_10; }) {
               inherit (finalAttrs) pname version src;
               fetcherVersion = 3;
-              hash = "sha256-hOqiAbnjKsoQnV8lgto5HspDsLIb+48sNLkShIjCZPQ=";
+              hash = "sha256-AzF/rrhqbvl613hNsC18YSylBSVxtatg7fEiUEF1u2o=";
             };
 
             buildPhase = ''

web/package.json

@@ -6,7 +6,7 @@
   "packageManager": "pnpm@9.15.4",
   "scripts": {
     "dev": "vite",
-    "build": "tsc -b && vite build",
+    "build": "tsc -b tsconfig.build.json && vite build",
     "preview": "vite preview",
     "typecheck": "tsc -b --noEmit",
     "test": "vitest run",

web/tsconfig.build.json

@@ -0,0 +1,8 @@
+{
+  // The nix derivation's src is `./web`, so the shared fixtures/ directory at
+  // the repo root does not exist there and `*.test.ts` cannot resolve its
+  // imports. Tests are not part of the shipped bundle; `pnpm typecheck` still
+  // checks them from a full checkout.
+  "extends": "./tsconfig.json",
+  "exclude": ["src/**/*.test.ts", "src/**/*.test.tsx"]
+}