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/openrouter/README.md

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+# OpenRouter：来源导航
+
+[总索引](../../README.md) · [官网证据与边界](SOURCES.md)
+
+本目录包含 15 个单模型文件、1 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/openrouter.json](access/providers--openrouter.md)
+
+## 模型
+
+- [`anthropic/claude-opus-5.5`](models/anthropic--claude-opus-5.5.md)
+- [`anthropic/claude-sonnet-5.5`](models/anthropic--claude-sonnet-5.5.md)
+- [`cohere/command-a-plus`](models/cohere--command-a-plus.md)
+- [`deepseek/deepseek-v4.1-flash`](models/deepseek--deepseek-v4.1-flash.md)
+- [`google/gemini-3.8-flash`](models/google--gemini-3.8-flash.md)
+- [`minimax/minimax-m3`](models/minimax--minimax-m3.md)
+- [`mistralai/mistral-medium-3-5`](models/mistralai--mistral-medium-3-5.md)
+- [`moonshotai/kimi-k3`](models/moonshotai--kimi-k3.md)
+- [`openai/gpt-6.1-sol`](models/openai--gpt-6.1-sol.md)
+- [`openrouter/auto`](models/openrouter--auto.md)
+- [`qwen/qwen3.8-max-prime`](models/qwen--qwen3.8-max-prime.md)
+- [`qwen/qwen3.8-omni-flash`](models/qwen--qwen3.8-omni-flash.md)
+- [`tencent/hy4-preview`](models/tencent--hy4-preview.md)
+- [`z-ai/glm-5.3`](models/z-ai--glm-5.3.md)
+- [`z-ai/glm-5.3-flash`](models/z-ai--glm-5.3-flash.md)