feat(logging): implement configurable belief state logging

- Add LoggingConfig model and logging field to GlobalSettings
- Implement belief_scope context manager for structured logging
- Add configure_logger for dynamic level and file rotation settings
- Add logging configuration UI to Settings page
- Update ConfigManager to apply logging settings on initialization and updates

backend/src/core/config_models.py

@@ -19,11 +19,22 @@ class Environment(BaseModel):
     is_default: bool = False
 # [/DEF:Environment]
 
+# [DEF:LoggingConfig:DataClass]
+# @PURPOSE: Defines the configuration for the application's logging system.
+class LoggingConfig(BaseModel):
+    level: str = "INFO"
+    file_path: Optional[str] = "logs/app.log"
+    max_bytes: int = 10 * 1024 * 1024
+    backup_count: int = 5
+    enable_belief_state: bool = True
+# [/DEF:LoggingConfig]
+
 # [DEF:GlobalSettings:DataClass]
 # @PURPOSE: Represents global application settings.
 class GlobalSettings(BaseModel):
     backup_path: str
     default_environment_id: Optional[str] = None
+    logging: LoggingConfig = Field(default_factory=LoggingConfig)
 # [/DEF:GlobalSettings]
 
 # [DEF:AppConfig:DataClass]