feat(gemini): implement video generation configuration and billing estimation

- Added Gemini video generation configuration structures and payloads.
- Introduced functions for parsing and resolving video duration and resolution from metadata.
- Enhanced the Vertex adaptor to support Gemini video generation requests and billing estimation based on duration and resolution.
- Updated model pricing settings for new Gemini video models.

relay/channel/task/gemini/image.go

@@ -0,0 +1,100 @@
+package gemini
+
+import (
+	"encoding/base64"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/QuantumNous/new-api/constant"
+	relaycommon "github.com/QuantumNous/new-api/relay/common"
+	"github.com/gin-gonic/gin"
+)
+
+const maxVeoImageSize = 20 * 1024 * 1024 // 20 MB
+
+// ExtractMultipartImage reads the first `input_reference` file from a multipart
+// form upload and returns a VeoImageInput. Returns nil if no file is present.
+func ExtractMultipartImage(c *gin.Context, info *relaycommon.RelayInfo) *VeoImageInput {
+	mf, err := c.MultipartForm()
+	if err != nil {
+		return nil
+	}
+	files, exists := mf.File["input_reference"]
+	if !exists || len(files) == 0 {
+		return nil
+	}
+	fh := files[0]
+	if fh.Size > maxVeoImageSize {
+		return nil
+	}
+	file, err := fh.Open()
+	if err != nil {
+		return nil
+	}
+	defer file.Close()
+
+	fileBytes, err := io.ReadAll(file)
+	if err != nil {
+		return nil
+	}
+
+	mimeType := fh.Header.Get("Content-Type")
+	if mimeType == "" || mimeType == "application/octet-stream" {
+		mimeType = http.DetectContentType(fileBytes)
+	}
+
+	info.Action = constant.TaskActionGenerate
+	return &VeoImageInput{
+		BytesBase64Encoded: base64.StdEncoding.EncodeToString(fileBytes),
+		MimeType:           mimeType,
+	}
+}
+
+// ParseImageInput parses an image string (data URI or raw base64) into a
+// VeoImageInput. Returns nil if the input is empty or invalid.
+// TODO: support downloading HTTP URL images and converting to base64
+func ParseImageInput(imageStr string) *VeoImageInput {
+	imageStr = strings.TrimSpace(imageStr)
+	if imageStr == "" {
+		return nil
+	}
+
+	if strings.HasPrefix(imageStr, "data:") {
+		return parseDataURI(imageStr)
+	}
+
+	raw, err := base64.StdEncoding.DecodeString(imageStr)
+	if err != nil {
+		return nil
+	}
+	return &VeoImageInput{
+		BytesBase64Encoded: imageStr,
+		MimeType:           http.DetectContentType(raw),
+	}
+}
+
+func parseDataURI(uri string) *VeoImageInput {
+	// data:image/png;base64,iVBOR...
+	rest := uri[len("data:"):]
+	idx := strings.Index(rest, ",")
+	if idx < 0 {
+		return nil
+	}
+	meta := rest[:idx]
+	b64 := rest[idx+1:]
+	if b64 == "" {
+		return nil
+	}
+
+	mimeType := "application/octet-stream"
+	parts := strings.SplitN(meta, ";", 2)
+	if len(parts) >= 1 && parts[0] != "" {
+		mimeType = parts[0]
+	}
+
+	return &VeoImageInput{
+		BytesBase64Encoded: b64,
+		MimeType:           mimeType,
+	}
+}