feat(city): add plaza exercise system with health tracking

- Adds CityPlazas support class for deterministic public plaza generation with outdoor gym equipment
- Implements exercise and stop-exercise actions with proximity validation to equipment
- Introduces health (0-100) and exercise_count attributes to Character model
- Reduces hospital stay duration from two game days to one game hour
- Adds 3D gym equipment rendering (bench, bars, bike, treadmill) in city viewer
- Includes exercise state machine handling in world ticker with energy drain
- Adds comprehensive PlazaExerciseTest and updates HospitalAdmissionTest
- Provides localized UI strings for health HUD and exercise prompts

database/migrations/2026_10_18_001000_add_hospitalized_until_to_characters_table.php

@@ -7,7 +7,7 @@ use Illuminate\Support\Facades\Schema;
 /**
  * Adds hospital admission tracking to characters.
  *
- * When a character is hit by a vehicle they are admitted for two game days
+ * When a character is hit by a vehicle they are admitted for one game hour
  * (hospitalized_until). The world ticker releases them automatically.
  */
 return new class extends Migration

database/migrations/2026_10_18_002000_add_health_to_characters_table.php

@@ -0,0 +1,35 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * Adds fitness tracking to characters.
+ *
+ * health is 0-100 and rises while the character exercises on public plaza
+ * equipment; exercise_count is a lifetime counter for progress display.
+ */
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('characters', function (Blueprint $table): void {
+            $table->unsignedTinyInteger('health')->default(100)->after('thirst');
+            $table->unsignedInteger('exercise_count')->default(0)->after('education');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('characters', function (Blueprint $table): void {
+            $table->dropColumn(['health', 'exercise_count']);
+        });
+    }
+};