chore: baseline snapshot before moderation-strictness feature

Repo .git was damaged (refs/ missing, index truncated, object store near-empty).
Repaired via git init (rebuilt refs), stale index preserved as .git/index.corrupt-20260910.bak,
then full worktree committed as a rollback baseline.

dev/webpstub/webp.go

@@ -0,0 +1,20 @@
+// webpstub（package webp）是 chai2010/webp 的本地编译桩：仅用于在缺少 libwebp 的
+// Windows 沙箱中通过 `go build -overlay` 对依赖 internal/storage 的包做完整
+// 类型检查。API 只覆盖项目实际用到的 Encode/Options。
+package webp
+
+import (
+	"image"
+	"io"
+)
+
+// Options 与 github.com/chai2010/webp 的 Options 字段保持兼容（项目仅用 Quality）。
+type Options struct {
+	Lossless bool
+	Quality  float32
+}
+
+// Encode 是 webp.Encode 的签名兼容桩（类型检查期间不会被真正调用）。
+func Encode(w io.Writer, m image.Image, o *Options) error {
+	return nil
+}