feat: add nerve config and Character nerve methods

Add nerve system configuration to config/game.php with start_amount,
max, regen_rate, regen_interval, and midnight_refill settings. Add gym
configuration with energy_cost, daily_cap, and stat_gain. Add nerve
methods to Character model: hasNerve(), consumeNerve(), addNerve(), and
getNervePercentageAttribute(). Update levelUp() to increment max_nerve
by 2. Add nerve_cost to fillable arrays in Crime and CrimeAttempt models.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Models/Character.php

@@ -50,6 +50,9 @@ class Character extends Model
         'max_energy',
         'health',
         'max_health',
+        'nerve',
+        'max_nerve',
+        'nerve_regen_at',
         'strength',
         'defense',
         'speed',
@@ -66,6 +69,7 @@ class Character extends Model
         'in_hospital_until' => 'datetime',
         'in_jail_until' => 'datetime',
         'last_action_at' => 'datetime',
+        'nerve_regen_at' => 'datetime',
         'status' => CharacterStatus::class,
     ];
 
@@ -251,6 +255,49 @@ class Character extends Model
         $this->save();
     }
 
+    /**
+     * Check if character has enough nerve for an action
+     */
+    public function hasNerve(int $amount): bool
+    {
+        return $this->nerve >= $amount;
+    }
+
+    /**
+     * Consume nerve
+     */
+    public function consumeNerve(int $amount): bool
+    {
+        if (!$this->hasNerve($amount)) {
+            return false;
+        }
+
+        $this->nerve -= $amount;
+        $this->save();
+
+        return true;
+    }
+
+    /**
+     * Add nerve (up to max)
+     */
+    public function addNerve(int $amount): void
+    {
+        $this->nerve = min($this->max_nerve, $this->nerve + $amount);
+        $this->save();
+    }
+
+    /**
+     * Get nerve percentage
+     */
+    public function getNervePercentageAttribute(): float
+    {
+        if ($this->max_nerve <= 0) {
+            return 0;
+        }
+        return min(100, ($this->nerve / $this->max_nerve) * 100);
+    }
+
     /**
      * Set energy to max
      */
@@ -317,6 +364,7 @@ class Character extends Model
         $this->experience -= $this->experience_for_next_level;
         $this->max_health += 5;
         $this->max_energy += 5;
+        $this->max_nerve += 2;
         $this->health = $this->max_health;
         $this->energy = $this->max_energy;
         $this->money += 1000;