docs: split model source records and unify project instructions (#113)

* docs: split model sources and consolidate project instructions

* docs: normalize empty model navigation footer

docs/model-sources/providers/google/README.md

@@ -0,0 +1,33 @@
+# Google Gemini：来源导航
+
+[总索引](../../README.md) · [官网证据与边界](SOURCES.md)
+
+本目录包含 20 个单模型文件、2 个单接入面文件。核验日期与状态来自迁移前记录。
+
+## 接入面
+
+- [compute/providers/google.json](access/providers--google.md)
+- [compute/model-specs/google.json](access/model-specs--google.md)
+
+## 模型
+
+- [`gemini-2.5-flash`](models/gemini-2.5-flash.md)
+- [`gemini-2.5-pro`](models/gemini-2.5-pro.md)
+- [`gemini-3-flash-preview`](models/gemini-3-flash-preview.md)
+- [`gemini-3.1-flash-image`](models/gemini-3.1-flash-image.md)
+- [`gemini-3.1-flash-lite`](models/gemini-3.1-flash-lite.md)
+- [`gemini-3.1-flash-lite-image`](models/gemini-3.1-flash-lite-image.md)
+- [`gemini-3.1-flash-lite-preview`](models/gemini-3.1-flash-lite-preview.md)
+- [`gemini-3.1-pro-preview`](models/gemini-3.1-pro-preview.md)
+- [`gemini-3.5-flash`](models/gemini-3.5-flash.md)
+- [`gemini-3.5-flash-lite`](models/gemini-3.5-flash-lite.md)
+- [`gemini-3.5-transcribe`](models/gemini-3.5-transcribe.md)
+- [`gemini-3.5-transcribe-live`](models/gemini-3.5-transcribe-live.md)
+- [`gemini-3.7-flash`](models/gemini-3.7-flash.md)
+- [`gemini-3.8-flash`](models/gemini-3.8-flash.md)
+- [`gemini-3.8-flash-lite-tts`](models/gemini-3.8-flash-lite-tts.md)
+- [`gemini-3.8-flash-tts`](models/gemini-3.8-flash-tts.md)
+- [`gemini-3.8-live`](models/gemini-3.8-live.md)
+- [`gemini-3.8-live-extended-thinking`](models/gemini-3.8-live-extended-thinking.md)
+- [`gemini-embedding-2`](models/gemini-embedding-2.md)
+- [`text-embedding-005`](models/text-embedding-005.md)