feat: 媒体库 blob 去重存储与品牌/注册等前端调整

新增：
- blob_store 二进制去重存储 + blob_dedup 测试

其它：
- 后端 settings/auth/media_library/upload/operations 服务与 handler 调整
- 前端品牌（BrandLockup/BrandCropModal/BrandSeoPanel）、注册、媒体库、分析详情页、Header/SiteChrome 等更新

frontend/components/BrandLockup.tsx

@@ -29,6 +29,8 @@ export default function BrandLockup({
   const showImage = mode !== "text";
   const showText = mode !== "image";
   const box = brandLogoBox(size);
+  // auto 图槽宽度随图（可达最宽画幅量级），按 176 取密度变体保证清晰
+  const cssPx = size === "auto" ? 176 : Math.max(box.w, box.h);
   const src = logoLight || logoDark;
   const both = !!(logoLight && logoDark && logoLight !== logoDark);
   const useBox = showImage && (!!src || frame);
@@ -41,16 +43,17 @@ export default function BrandLockup({
             className="j13-brand-slot"
             data-frame={frame ? "1" : undefined}
             data-fit={src ? fit : undefined}
-            style={{ width: box.w, height: box.h }}
+            data-size={size}
+            style={{ width: box.w || undefined, height: box.h }}
           >
             {src ? (
               both ? (
                 <>
-                  <Logo src={logoLight} fit={fit} alt={label} decorative={showText} extra="j13-brand-logo-light" cssPx={Math.max(box.w, box.h)} />
-                  <Logo src={logoDark} fit={fit} alt={label} decorative={showText} extra="j13-brand-logo-dark" cssPx={Math.max(box.w, box.h)} />
+                  <Logo src={logoLight} fit={fit} alt={label} decorative={showText} extra="j13-brand-logo-light" cssPx={cssPx} />
+                  <Logo src={logoDark} fit={fit} alt={label} decorative={showText} extra="j13-brand-logo-dark" cssPx={cssPx} />
                 </>
               ) : (
-                <Logo src={src} fit={fit} alt={label} decorative={showText} cssPx={Math.max(box.w, box.h)} />
+                <Logo src={src} fit={fit} alt={label} decorative={showText} cssPx={cssPx} />
               )
             ) : (
               <Bubble h={box.h} label={showText ? undefined : label} />