Implement ticket links and blocker state

app/Models/Ticket.php

@@ -12,7 +12,9 @@ use Illuminate\Database\Eloquent\Relations\HasMany;
 #[Fillable([
     'acceptance_criteria',
     'board_column_id',
+    'blocked_comment',
     'description',
+    'is_blocked',
     'parent_ticket_id',
     'project_id',
     'sequence_number',
@@ -26,6 +28,16 @@ class Ticket extends Model
     /** @use HasFactory<TicketFactory> */
     use HasFactory;
 
+    /**
+     * @return array<string, string>
+     */
+    protected function casts(): array
+    {
+        return [
+            'is_blocked' => 'boolean',
+        ];
+    }
+
     public function boardColumn(): BelongsTo
     {
         return $this->belongsTo(BoardColumn::class);
@@ -48,6 +60,18 @@ class Ticket extends Model
         return $this->belongsTo(Ticket::class, 'parent_ticket_id');
     }
 
+    public function ticketLinksAsSource(): HasMany
+    {
+        return $this->hasMany(TicketLink::class, 'source_ticket_id')
+            ->orderBy('id');
+    }
+
+    public function ticketLinksAsTarget(): HasMany
+    {
+        return $this->hasMany(TicketLink::class, 'target_ticket_id')
+            ->orderBy('id');
+    }
+
     public function project(): BelongsTo
     {
         return $this->belongsTo(Project::class);