chore: gitignore .research, switch to flash, tighten sub-questions

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

.gitignore

@@ -82,6 +82,9 @@ htmlcov/
 # Package 3 — SQLite databases
 data/
 
+# Research
+.research/
+
 # Misc
 *.bak
 *.tmp

backend/app/core/config.py

@@ -18,7 +18,7 @@ class Settings(BaseSettings):
     # Deepseek API (decompose step only, Package 6)
     dp_base_url: str = "https://api.deepseek.com"
     dp_api_key: str = ""
-    dp_model_name: str = "deepseek-v4-pro"
+    dp_model_name: str = "deepseek-v4-flash"
 
     # Embeddings
     embedding_model: str = "qwen/qwen3-embedding-4b"

backend/app/models/decompose.py

@@ -9,7 +9,7 @@ class SubQuestions(BaseModel):
     """
 
     questions: list[str] = Field(
-        description="1-3 simplified sub-questions, each focused on one aspect並總格成以下格式 '標籤式主題: 具體提問/要求' ",
+        description="請將問題/任務拆解成 1-3 個簡化子問題，標籤式主題必須清楚、簡潔、具體，一看就明白（建議 3-8 個字），若涉及地點、地區、人物、時間、金額/財政 等關鍵資訊，必須包含在標籤中 。具體提問/要求要精準、完整 並全部轉換成以下固定格式：\n「標籤式主題：具體提問/要求」",
         min_length=1,
         max_length=3,
     )