feat(city): add player marketplace, mission journal, character customization and presence

- Player-to-player marketplace with listings, buying and selling
- Mission system with progress tracking and money rewards
- Character appearance customization (skin, hair, face, beard, accessory)
- Multiplayer presence feed showing nearby citizens in near-real-time
- Admin world dashboard with live platform metrics
- Bus and train transportation with temporary ride state
- Mobile joystick controls and minimap HUD
- Education bonus applied to work salary

app/Models/Mission.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Attributes\Fillable;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+
+/**
+ * Catalog mission that citizens can complete for a reward.
+ */
+#[Fillable(['city_id', 'code', 'title', 'description', 'metric', 'target', 'reward', 'is_active'])]
+class Mission extends Model
+{
+    /**
+     * Characters tracking this mission.
+     *
+     * @return BelongsToMany<Character, $this>
+     */
+    public function characters(): BelongsToMany
+    {
+        return $this->belongsToMany(Character::class, 'character_missions')
+            ->withPivot(['progress', 'is_completed', 'completed_at'])
+            ->withTimestamps();
+    }
+
+    /**
+     * Get the attributes that should be cast.
+     *
+     * @return array<string, string>
+     */
+    protected function casts(): array
+    {
+        return [
+            'reward' => 'float',
+            'target' => 'integer',
+            'is_active' => 'boolean',
+        ];
+    }
+}