fix: resolve pylint and type-checking issues

- Fix return type annotation in SetupRedirectMiddleware.dispatch() to use Response instead of RedirectResponse
- Replace broad 'except Exception' with specific exception types (FileNotFoundError, ValueError, OSError, etc.)
- Rename AppConfig.validate() to validate_config() to avoid shadowing BaseModel.validate()
- Fix ValidationResult.errors field to use List[str] with default_factory
- Add pylint disable comments for intentional broad exception catches during shutdown
- Rename lifespan parameter to _application to indicate unused variable
- Update all callers to use new validate_config() method name

src/server/models/config.py

@@ -58,8 +58,9 @@ class ValidationResult(BaseModel):
     """Result of a configuration validation attempt."""
 
     valid: bool = Field(..., description="Whether the configuration is valid")
-    errors: Optional[List[str]] = Field(
-        default_factory=list, description="List of validation error messages"
+    errors: List[str] = Field(
+        default_factory=lambda: [],
+        description="List of validation error messages"
     )
 
 
@@ -71,14 +72,16 @@ class AppConfig(BaseModel):
 
     name: str = Field(default="Aniworld", description="Application name")
     data_dir: str = Field(default="data", description="Base data directory")
-    scheduler: SchedulerConfig = Field(default_factory=SchedulerConfig)
+    scheduler: SchedulerConfig = Field(
+        default_factory=SchedulerConfig
+    )
     logging: LoggingConfig = Field(default_factory=LoggingConfig)
     backup: BackupConfig = Field(default_factory=BackupConfig)
     other: Dict[str, object] = Field(
         default_factory=dict, description="Arbitrary other settings"
     )
 
-    def validate(self) -> ValidationResult:
+    def validate_config(self) -> ValidationResult:
         """Perform light-weight validation and return a ValidationResult.
 
         This method intentionally avoids performing IO (no filesystem checks)
@@ -98,7 +101,8 @@ class AppConfig(BaseModel):
                 errors.append(msg)
 
         # backup.path must be set when backups are enabled
-        if self.backup.enabled and (not self.backup.path):
+        backup_data = self.model_dump().get("backup", {})
+        if backup_data.get("enabled") and not backup_data.get("path"):
             errors.append(
                 "backup.path must be set when backups.enabled is true"
             )