feat(ui): streamline workspace settings and remove sharing

Unify compact workspace controls and panel transitions, move directory actions into the context menu, and remove backlink UI.

Reorganize settings with searchable sections, per-setting resets, shortcut search, and accurate save feedback.

Remove sharing UI, APIs, authentication helpers, and storage code; provide a transactional cleanup script with retirement tests. Reject directories during orphan image cleanup and cover mixed-batch preservation.

internal/api/themes_test.go

@@ -1,8 +1,6 @@
 package api
 
 import (
-	"encoding/json"
-	"io"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -10,7 +8,7 @@ import (
 	"testing"
 )
 
-func TestThemeAndShareAppearanceBoundaries(t *testing.T) {
+func TestThemeBoundaries(t *testing.T) {
 	f := newFixture(t)
 	dir := filepath.Join(filepath.Dir(f.root), "themes", "paper")
 	if err := os.MkdirAll(dir, 0o755); err != nil {
@@ -42,33 +40,6 @@ func TestThemeAndShareAppearanceBoundaries(t *testing.T) {
 	if !strings.Contains(theme["css"], "#faf6ed") {
 		t.Fatal("未读取到主题 CSS")
 	}
-	f.write("笔记.md", "正文")
-	f.do(f.admin, "PATCH", "/api/v1/settings", `{"theme":"paper","colorMode":"dark","fontSize":18,"uiFontSize":20,"privateSetting":"不公开","cssSnippets":[{"id":"a","name":"启用","css":"body { color: red }","enabled":true},{"id":"b","name":"停用","css":"不公开片段","enabled":false}]}`, nil)
-	sh := decode[shareView](t, f.do(f.admin, "POST", "/api/v1/shares", `{"path":"笔记.md","password":"访问密码"}`, nil))
-	base := "/api/v1/public/shares/" + sh.Token
-	if code := f.status(guest, "GET", base+"/appearance", "", nil); code != 401 {
-		t.Fatalf("未解锁不能读取外观，得到 %d", code)
-	}
-	f.do(guest, "POST", base+"/unlock", `{"password":"访问密码"}`, nil)
-	res := f.do(guest, "GET", base+"/appearance", "", nil)
-	raw, err := io.ReadAll(res.Body)
-	if err != nil {
-		t.Fatal(err)
-	}
-	var appearance map[string]any
-	if err := json.Unmarshal(raw, &appearance); err != nil {
-		t.Fatal(err)
-	}
-	if res.StatusCode != 200 || appearance["colorMode"] != "dark" || appearance["uiFontSize"] != float64(20) || appearance["fontSize"] != float64(18) || !strings.Contains(appearance["themeCSS"].(string), "#faf6ed") {
-		t.Fatalf("分享外观错误：%s", raw)
-	}
-	if strings.Contains(string(raw), "不公开") || len(appearance["cssSnippets"].([]any)) != 1 {
-		t.Fatalf("分享泄露了其他设置或停用片段：%s", raw)
-	}
-	f.do(f.admin, "DELETE", "/api/v1/shares/"+sh.Token, "", nil)
-	if code := f.status(guest, "GET", base+"/appearance", "", nil); code != 404 {
-		t.Fatalf("撤销分享后不能读取外观，得到 %d", code)
-	}
 	// CSS 符号链接不能读取主题目录之外的应用数据。
 	if err := os.Remove(filepath.Join(dir, "theme.css")); err != nil {
 		t.Fatal(err)