feat: add Google Gemini API support (#1418)

* feat: add Google Gemini API support

Co-Authored-By: Junyan Qin <Chin> <rockchinq@gmail.com>

* fix: remove unused imports

Co-Authored-By: Junyan Qin <Chin> <rockchinq@gmail.com>

* feat: add google-genai dependency

Co-Authored-By: Junyan Qin <Chin> <rockchinq@gmail.com>

* fix: update Gemini API implementation to use correct API methods

Co-Authored-By: Junyan Qin <Chin> <rockchinq@gmail.com>

* refactor: improve Gemini API implementation based on official documentation

Co-Authored-By: Junyan Qin <Chin> <rockchinq@gmail.com>

* fix: remove unsupported timeout parameter from Gemini API implementation

Co-Authored-By: Junyan Qin <Chin> <rockchinq@gmail.com>

* fix: correct Gemini API implementation based on official documentation

Co-Authored-By: Junyan Qin <Chin> <rockchinq@gmail.com>

* feat: update geminichatcmpl

* deps: add google-generativeai

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: Junyan Qin <Chin> <rockchinq@gmail.com>

pkg/provider/modelmgr/requesters/geminichatcmpl.yaml

@@ -0,0 +1,28 @@
+apiVersion: v1
+kind: LLMAPIRequester
+metadata:
+  name: gemini-chat-completions
+  label:
+    en_US: Google Gemini
+    zh_CN: Google Gemini
+  icon: gemini.svg
+spec:
+  config:
+    - name: base_url
+      label:
+        en_US: Base URL
+        zh_CN: 基础 URL
+      type: string
+      required: true
+      default: "https://generativelanguage.googleapis.com"
+    - name: timeout
+      label:
+        en_US: Timeout
+        zh_CN: 超时时间
+      type: integer
+      required: true
+      default: 120
+execution:
+  python:
+    path: ./geminichatcmpl.py
+    attr: GeminiChatCompletions