Refactor skill allocation to upgrade; implement skill requirements and resource checks; remove experience from Pet model; update README for skill tree progress

Repositories/PetSkillRepository.cs

@@ -13,10 +13,19 @@ namespace PetCompanion.Repositories
             _context = context;
         }
 
+        public IEnumerable<Skill> GetAvailableSkills()
+        {
+            return _context.Skills
+                .Include(s => s.Effects)
+                .Include(s => s.SkillRequirements)
+                .ToList();
+        }
+
         public Skill GetSkill(int id)
         {
             return _context.Skills
                 .Include(s => s.Effects)
+                .Include(s => s.SkillRequirements)
                 .FirstOrDefault(s => s.Id == id);
         }