fix(asana): remove MySQL-specific gorm type tags for PostgreSQL compatibility (#8836)

Remove explicit `gorm:"type:double"` and `gorm:"type:int unsigned"` tags
from the Asana task migration struct. PostgreSQL does not have a `double`
type (it uses `double precision`) and does not support `UNSIGNED` integer
qualifiers. Without explicit tags, GORM infers the correct column type
per dialect automatically.

Follows the same pattern as #8779 which fixed equivalent issues in the
copilot plugin.

closes #8835

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Klesh Wong <klesh@qq.com>

Author: 3 people

backend/plugins/asana/models/migrationscripts/20250212_add_task_transformation_fields.go

@@ -34,7 +34,7 @@ type asanaTask20250212 struct {
 	Priority        string   `gorm:"type:varchar(255)"`
 	StoryPoint      *float64 `gorm:"type:float8"`
 	Severity        string   `gorm:"type:varchar(255)"`
-	LeadTimeMinutes *uint    `gorm:"type:int unsigned"`
+	LeadTimeMinutes *uint
 }
 
 func (asanaTask20250212) TableName() string {