fix: auto-fix code issues (cron)

- 修复重复导入/字段
- 修复异常处理 (将裸 except Exception 改为具体异常类型)
- 修复PEP8格式问题
- 清理未使用导入
- 添加 UUID_LENGTH 常量替代魔法数字
- 添加 DEFAULT_RATE_LIMIT, MASTER_KEY_RATE_LIMIT, IP_RATE_LIMIT 常量
- 添加 MAX_TEXT_LENGTH, DEFAULT_TIMEOUT 常量

涉及文件:
- backend/main.py
- backend/db_manager.py
- backend/llm_client.py
- backend/neo4j_manager.py
- backend/tingwu_client.py
- backend/tenant_manager.py
- backend/growth_manager.py
- backend/workflow_manager.py
- backend/image_processor.py
- backend/multimodal_entity_linker.py
- backend/multimodal_processor.py
- backend/plugin_manager.py
- backend/rate_limiter.py

backend/db_manager.py

@@ -14,6 +14,10 @@ from datetime import datetime
 
 DB_PATH = os.getenv("DB_PATH", "/app/data/insightflow.db")
 
+# Constants
+UUID_LENGTH = 8  # UUID 截断长度
+
+
 @dataclass
 class Project:
     id: str
@@ -22,6 +26,7 @@ class Project:
     created_at: str = ""
     updated_at: str = ""
 
+
 @dataclass
 class Entity:
     id: str
@@ -42,6 +47,7 @@ class Entity:
         if self.attributes is None:
             self.attributes = {}
 
+
 @dataclass
 class AttributeTemplate:
     """属性模板定义"""
@@ -62,6 +68,7 @@ class AttributeTemplate:
         if self.options is None:
             self.options = []
 
+
 @dataclass
 class EntityAttribute:
     """实体属性值"""
@@ -82,6 +89,7 @@ class EntityAttribute:
         if self.options is None:
             self.options = []
 
+
 @dataclass
 class AttributeHistory:
     """属性变更历史"""
@@ -95,6 +103,7 @@ class AttributeHistory:
     changed_at: str = ""
     change_reason: str = ""
 
+
 @dataclass
 class EntityMention:
     id: str
@@ -105,6 +114,7 @@ class EntityMention:
     text_snippet: str
     confidence: float = 1.0
 
+
 class DatabaseManager:
     def __init__(self, db_path: str = DB_PATH):
         self.db_path = db_path
@@ -321,15 +331,14 @@ class DatabaseManager:
         conn.execute(
             """INSERT INTO entity_mentions (id, entity_id, transcript_id, start_pos, end_pos, text_snippet, confidence)
                VALUES (?, ?, ?, ?, ?, ?, ?)""",
-            (
-                mention.id,
-                mention.entity_id,
-                mention.transcript_id,
-                mention.start_pos,
-                mention.end_pos,
-                mention.text_snippet,
-                mention.confidence,
-            ),
+            (mention.id,
+             mention.entity_id,
+             mention.transcript_id,
+             mention.start_pos,
+             mention.end_pos,
+             mention.text_snippet,
+             mention.confidence,
+             ),
         )
         conn.commit()
         conn.close()
@@ -358,7 +367,12 @@ class DatabaseManager:
         now = datetime.now().isoformat()
         conn.execute(
             "INSERT INTO transcripts (id, project_id, filename, full_text, type, created_at) VALUES (?, ?, ?, ?, ?, ?)",
-            (transcript_id, project_id, filename, full_text, transcript_type, now),
+            (transcript_id,
+             project_id,
+             filename,
+             full_text,
+             transcript_type,
+             now),
         )
         conn.commit()
         conn.close()
@@ -401,7 +415,7 @@ class DatabaseManager:
         transcript_id: str = "",
     ):
         conn = self.get_conn()
-        relation_id = str(uuid.uuid4())[:8]
+        relation_id = str(uuid.uuid4())[:UUID_LENGTH]
         now = datetime.now().isoformat()
         conn.execute(
             """INSERT INTO entity_relations
@@ -485,7 +499,7 @@ class DatabaseManager:
             conn.close()
             return existing["id"]
 
-        term_id = str(uuid.uuid4())[:8]
+        term_id = str(uuid.uuid4())[:UUID_LENGTH]
         conn.execute(
             "INSERT INTO glossary (id, project_id, term, pronunciation, frequency) VALUES (?, ?, ?, ?, ?)",
             (term_id, project_id, term, pronunciation, 1),
@@ -836,7 +850,7 @@ class DatabaseManager:
                    (id, entity_id, template_id, old_value, new_value, changed_by, changed_at, change_reason)
                    VALUES (?, ?, ?, ?, ?, ?, ?, ?)""",
                 (
-                    str(uuid.uuid4())[:8],
+                    str(uuid.uuid4())[:UUID_LENGTH],
                     attr.entity_id,
                     attr.template_id,
                     old_value,
@@ -915,7 +929,7 @@ class DatabaseManager:
                    (id, entity_id, template_id, old_value, new_value, changed_by, changed_at, change_reason)
                    VALUES (?, ?, ?, ?, ?, ?, ?, ?)""",
                 (
-                    str(uuid.uuid4())[:8],
+                    str(uuid.uuid4())[:UUID_LENGTH],
                     entity_id,
                     template_id,
                     old_row["value"],
@@ -1387,9 +1401,11 @@ class DatabaseManager:
         conn.close()
         return stats
 
+
 # Singleton instance
 _db_manager = None
 
+
 def get_db_manager() -> DatabaseManager:
     global _db_manager
     if _db_manager is None: