feat: add admin publishing workflow and yar theme

Add Go/Postgres admin APIs, Angular admin UI, manual build flow, asset uploads, markdown import/export, configurable slug generation, and the Yar reading theme. Exclude local docs and generated development artifacts from version control.

backend/internal/cli/config_test.go

@@ -1,25 +1,19 @@
 package cli
 
-import "testing"
+import (
+	"strings"
+	"testing"
+)
 
-func TestChangedConfigFields(t *testing.T) {
-	var a siteConfigFile
-	a.Meta.ConfigVersion = 1
-	a.Meta.UpdatedAt = "2026-05-28T12:00:00+08:00"
-	a.Site.Title = "A"
-	a.Content.PostsDir = "content/posts"
-	a.Build.OutputDir = "dist/site"
-
-	b := a
-	if fields := changedConfigFields(a, b); len(fields) != 0 {
-		t.Fatalf("unchanged config fields = %#v", fields)
+func TestRunConfigReportsLocalOnly(t *testing.T) {
+	err := runConfig(t.TempDir(), nil)
+	if err == nil || !strings.Contains(err.Error(), "local-file-only") {
+		t.Fatalf("expected local-file-only error, got %v", err)
 	}
 
-	b.Site.Title = "B"
-	b.Build.OutputDir = "dist/other"
-	fields := changedConfigFields(a, b)
-	if len(fields) != 2 || fields[0] != "site.title" || fields[1] != "build.output_dir" {
-		t.Fatalf("changed fields = %#v", fields)
+	err = runConfig(t.TempDir(), []string{"sync"})
+	if err == nil || !strings.Contains(err.Error(), "unsupported subcommand \"sync\"") {
+		t.Fatalf("expected unsupported subcommand error, got %v", err)
 	}
 }