admin lists: server-side pagination + filters for accounts/users/cdks/showcase/banned-words (limit/offset/total; stats over full set; /showcase/admin flat paginated view; dead=1 accounts filter for bulk dead-delete)

backend/internal/http/handler/pagination.go

@@ -0,0 +1,33 @@
+package handler
+
+import "github.com/gin-gonic/gin"
+
+// pageParams reads limit/offset query params with the given default page size.
+// A limit of 0 (or negative) is treated as "return everything" so callers that
+// need the full filtered set (e.g. bulk actions) can pass ?limit=0.
+func pageParams(c *gin.Context, defLimit int) (limit, offset int) {
+	limit = parseInt(c.Query("limit"), defLimit)
+	if limit < 0 {
+		limit = 0
+	}
+	offset = parseInt(c.Query("offset"), 0)
+	if offset < 0 {
+		offset = 0
+	}
+	return limit, offset
+}
+
+// pageSlice returns items[offset : offset+limit], clamped to the slice bounds.
+// limit <= 0 means "from offset to the end". Always returns a non-nil slice so
+// it JSON-encodes as [] rather than null.
+func pageSlice[T any](items []T, limit, offset int) []T {
+	n := len(items)
+	if offset >= n {
+		return []T{}
+	}
+	end := n
+	if limit > 0 && offset+limit < n {
+		end = offset + limit
+	}
+	return items[offset:end]
+}