feat: add primary tag functionality to tasks

- Introduced `primaryTagId` to `Task` model and updated related components to support selecting a primary tag.
- Enhanced `TaskCard`, `EditTaskForm`, and `TagInput` to handle primary tag selection and display.
- Updated `TasksService` to manage primary tag data during task creation and updates.
- Added `emoji-regex` dependency for improved emoji handling in task titles.

prisma/schema.prisma

@@ -46,6 +46,8 @@ model Task {
   tfsRepository    String?
   tfsSourceBranch  String?
   tfsTargetBranch  String?
+  primaryTagId     String?
+  primaryTag       Tag?            @relation("PrimaryTag", fields: [primaryTagId], references: [id])
   dailyCheckboxes  DailyCheckbox[]
   taskTags         TaskTag[]
 
@@ -54,11 +56,12 @@ model Task {
 }
 
 model Tag {
-  id       String    @id @default(cuid())
-  name     String    @unique
-  color    String    @default("#6b7280")
-  isPinned Boolean   @default(false)
-  taskTags TaskTag[]
+  id           String    @id @default(cuid())
+  name         String    @unique
+  color        String    @default("#6b7280")
+  isPinned     Boolean   @default(false)
+  taskTags     TaskTag[]
+  primaryTasks Task[]    @relation("PrimaryTag")
 
   @@map("tags")
 }