feat(issues): notificaciones, plantillas de checklist, alertas de vencimiento y reporte desde el mapa

- Notificaciones (DB): asignación de incidencia (IssueAssigned), asignación de tarea
  (IssueTaskAssigned), comentario (IssueCommented) y cambio de estado
  (IssueStatusChanged) a reporter+asignado excluyendo al actor.
- Plantillas de checklist: tabla issue_checklist_templates + modelo, gestor CRUD
  (IssueChecklistManager, ruta projects.issues.checklists) y "Aplicar plantilla" en
  el detalle (alta masiva de tareas).
- Alertas de vencimiento: columna overdue_notified_at + scope overdue, comando
  issues:notify-overdue (programado a diario) que avisa al asignado una sola vez;
  badge "vencidas" en la tabla y resaltado por tarea en el detalle.
- Reporte desde el mapa: botón "Incidencia" en el panel del feature seleccionado →
  formulario con feature pre-vinculado (IssueForm lee ?feature=).

Tests: IssuesEnhancementsTest (7). Suite 57 passing (solo 2 pre-existentes sqlite).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/Models/IssueChecklistTemplate.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class IssueChecklistTemplate extends Model
+{
+    use SoftDeletes;
+
+    protected $fillable = ['project_id', 'name', 'items'];
+
+    protected $casts = ['items' => 'array'];
+
+    public function project()
+    {
+        return $this->belongsTo(Project::class);
+    }
+}

app/Models/IssueTask.php

@@ -11,16 +11,25 @@ class IssueTask extends Model
 
     protected $fillable = [
         'issue_id', 'title', 'is_done', 'done_at', 'done_by',
-        'assigned_to', 'due_date', 'order',
+        'assigned_to', 'due_date', 'order', 'overdue_notified_at',
         'uuid', 'client_updated_at',
     ];
 
     protected $casts = [
-        'is_done'  => 'boolean',
-        'done_at'  => 'datetime',
-        'due_date' => 'date',
+        'is_done'             => 'boolean',
+        'done_at'             => 'datetime',
+        'due_date'            => 'date',
+        'overdue_notified_at' => 'datetime',
     ];
 
+    /** Tasks that are past their due date and not yet completed. */
+    public function scopeOverdue($q)
+    {
+        return $q->where('is_done', false)
+                 ->whereNotNull('due_date')
+                 ->whereDate('due_date', '<', now()->toDateString());
+    }
+
     public function issue()     { return $this->belongsTo(Issue::class); }
     public function assignee()  { return $this->belongsTo(User::class, 'assigned_to'); }
     public function completer() { return $this->belongsTo(User::class, 'done_by'); }