Decouple Go build/test/lint from frontend asset compilation

Add a production build tag to assets.go so the dist/ embed directives
only apply when building with -tags production. A new assets_dev.go
provides stub values for development, tests, and linting — no Vite
build required. CI lint and test jobs no longer need Node.js/pnpm;
build-assets is moved exclusively into the build job.

Also use -tags production for `just run` so local dev has real assets
in the browser, and add manifest_test.go to cover NewManifest with a
realistic Vite manifest fixture.

Author: pierres

.github/actions/setup/action.yml

@@ -27,9 +27,6 @@ runs:
       run: just install
       shell: bash
 
-    - name: Build Assets
-      run: just build-assets
-      shell: bash
     - name: Build Templates
       run: just build-templates
       shell: bash

.github/workflows/ci.yml

@@ -33,5 +33,7 @@ jobs:
               uses: actions/checkout@v5
             - name: Run Common Setup
               uses: ./.github/actions/setup
+            - name: Build Assets
+              run: just build-assets
             - name: Build Application
               run: just build

assets.go

@@ -1,3 +1,5 @@
+//go:build production
+
 package main
 
 import "embed"

assets_dev.go

@@ -0,0 +1,12 @@
+//go:build !production
+
+package main
+
+import "embed"
+
+var embedAssets embed.FS
+
+//go:embed static
+var embedStatic embed.FS
+
+var embedManifest = []byte(`{}`)

internal/ui/layout/manifest_test.go

@@ -0,0 +1,85 @@
+package layout
+
+import (
+	"testing"
+)
+
+// realManifest mirrors the structure produced by Vite: one entry point with
+// CSS, several non-entry chunks (dynamic imports, vendor splits, etc.).
+var realManifest = []byte(`{
+  "__commonjsHelpers-CLPN-Npl.js": {
+    "file": "assets/_commonjsHelpers-CLPN-Npl.js",
+    "name": "_commonjsHelpers"
+  },
+  "_index-BmL2jti6.js": {
+    "file": "assets/index-BmL2jti6.js",
+    "name": "index"
+  },
+  "_index-bUj5cbfw.js": {
+    "file": "assets/index-bUj5cbfw.js",
+    "name": "index",
+    "isDynamicEntry": true,
+    "imports": ["_index-BmL2jti6.js"]
+  },
+  "node_modules/.pnpm/chart.js@4.5.1/node_modules/chart.js/dist/chart.js": {
+    "file": "assets/chart-BjMzFfek.js",
+    "name": "chart",
+    "isDynamicEntry": true
+  },
+  "src/main.ts": {
+    "file": "assets/main-CxdDuL5j.js",
+    "name": "main",
+    "src": "src/main.ts",
+    "isEntry": true,
+    "dynamicImports": ["node_modules/.pnpm/chart.js@4.5.1/node_modules/chart.js/dist/chart.js"],
+    "css": ["assets/main-QTw0RKdw.css"]
+  }
+}`)
+
+func TestNewManifest_ParsesEntryPoint(t *testing.T) {
+	manifest, err := NewManifest(realManifest)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(manifest.JS) != 1 || manifest.JS[0] != "/assets/main-CxdDuL5j.js" {
+		t.Errorf("JS = %v, want [/assets/main-CxdDuL5j.js]", manifest.JS)
+	}
+
+	if len(manifest.CSS) != 1 || manifest.CSS[0] != "/assets/main-QTw0RKdw.css" {
+		t.Errorf("CSS = %v, want [/assets/main-QTw0RKdw.css]", manifest.CSS)
+	}
+}
+
+func TestNewManifest_SkipsNonEntryChunks(t *testing.T) {
+	manifest, err := NewManifest(realManifest)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(manifest.JS) != 1 {
+		t.Errorf("expected 1 JS entry, got %d: %v", len(manifest.JS), manifest.JS)
+	}
+
+	if len(manifest.CSS) != 1 {
+		t.Errorf("expected 1 CSS entry, got %d: %v", len(manifest.CSS), manifest.CSS)
+	}
+}
+
+func TestNewManifest_EmptyManifest(t *testing.T) {
+	manifest, err := NewManifest([]byte(`{}`))
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(manifest.JS) != 0 || len(manifest.CSS) != 0 {
+		t.Errorf("expected empty manifest, got JS=%v CSS=%v", manifest.JS, manifest.CSS)
+	}
+}
+
+func TestNewManifest_InvalidJSON(t *testing.T) {
+	_, err := NewManifest([]byte(`not json`))
+	if err == nil {
+		t.Error("expected error for invalid JSON, got nil")
+	}
+}

justfile

@@ -23,10 +23,10 @@ build-templates:
     go tool templ generate
 
 build: build-assets build-templates
-    go build -o pkgstatsd -ldflags="-s -w" -trimpath
+    go build -tags production -o pkgstatsd -ldflags="-s -w" -trimpath
 
 run:
-    go run .
+    go run -tags production .
 
 test:
     go test ./...