Add comprehensive spell sound manager with 35+ magic sounds

Implemented complete spell casting audio system with all magic schools:

Magic schools supported:
- Fire: Precast (Low/Medium/High), Cast, Fireball impacts
- Frost: Precast (Low/Medium/High), Cast, Blizzard impacts
- Holy: Precast (Low/Medium/High), Cast, Holy impacts (4 levels)
- Nature: Precast (Low/Medium/High), Cast
- Shadow: Precast (Low/Medium/High), Cast
- Arcane: Precast, Arcane Missile impacts
- Physical: Non-magical abilities

Spell phases:
- Precast: Channeling/preparation sounds (before cast)
- Cast: Spell release sounds (when spell fires)
- Impact: Spell hit sounds (when spell hits target)

Power levels:
- Low: Weak spells, low level abilities
- Medium: Standard power spells
- High: Powerful high-level spells

Sound coverage (35+ sounds):
- 16 precast sounds (Fire/Frost/Holy/Nature/Shadow × Low/Med/High + Arcane)
- 5 cast sounds (one per school)
- 16 impact sounds (Fireball ×3, Blizzard ×6, Holy ×4, Arcane Missile ×3)

Technical details:
- Loads 35+ sound files from Sound\Spells directory
- Simple API: playPrecast(school, power), playCast(school), playImpact(school, power)
- Convenience methods: playFireball(), playFrostbolt(), playHeal(), etc.
- Random variation selection for impacts
- Volume at 0.75 with global scale control
- Ready for integration with spell casting system

Usage examples:
```cpp
// Full spell sequence
spellSoundManager->playPrecast(MagicSchool::FIRE, SpellPower::HIGH);
// ... cast time ...
spellSoundManager->playCast(MagicSchool::FIRE);
// ... projectile travel ...
spellSoundManager->playImpact(MagicSchool::FIRE, SpellPower::HIGH);

// Convenience methods
spellSoundManager->playFireball();
spellSoundManager->playHeal();
```

This adds essential magic feedback for spell casting gameplay!

include/audio/spell_sound_manager.hpp

@@ -0,0 +1,106 @@
+#pragma once
+
+#include <vector>
+#include <memory>
+#include <string>
+#include <cstdint>
+
+namespace wowee {
+namespace pipeline {
+class AssetManager;
+}
+
+namespace audio {
+
+class SpellSoundManager {
+public:
+    SpellSoundManager() = default;
+    ~SpellSoundManager() = default;
+
+    // Initialization
+    bool initialize(pipeline::AssetManager* assets);
+    void shutdown();
+
+    // Volume control
+    void setVolumeScale(float scale);
+
+    // Magic school types
+    enum class MagicSchool {
+        FIRE,
+        FROST,
+        HOLY,
+        NATURE,
+        SHADOW,
+        ARCANE,
+        PHYSICAL  // Non-magical abilities
+    };
+
+    // Spell power level
+    enum class SpellPower {
+        LOW,      // Weak spells, low level
+        MEDIUM,   // Standard spells
+        HIGH      // Powerful spells
+    };
+
+    // Spell casting sounds
+    void playPrecast(MagicSchool school, SpellPower power);  // Channeling/preparation
+    void playCast(MagicSchool school);                        // When spell fires
+    void playImpact(MagicSchool school, SpellPower power);    // When spell hits target
+
+    // Specific spell sounds
+    void playFireball();
+    void playFrostbolt();
+    void playLightningBolt();
+    void playHeal();
+    void playShadowBolt();
+
+private:
+    struct SpellSample {
+        std::string path;
+        std::vector<uint8_t> data;
+        bool loaded;
+    };
+
+    // Precast sound libraries (channeling)
+    std::vector<SpellSample> precastFireLowSounds_;
+    std::vector<SpellSample> precastFireMediumSounds_;
+    std::vector<SpellSample> precastFireHighSounds_;
+    std::vector<SpellSample> precastFrostLowSounds_;
+    std::vector<SpellSample> precastFrostMediumSounds_;
+    std::vector<SpellSample> precastFrostHighSounds_;
+    std::vector<SpellSample> precastHolyLowSounds_;
+    std::vector<SpellSample> precastHolyMediumSounds_;
+    std::vector<SpellSample> precastHolyHighSounds_;
+    std::vector<SpellSample> precastNatureLowSounds_;
+    std::vector<SpellSample> precastNatureMediumSounds_;
+    std::vector<SpellSample> precastNatureHighSounds_;
+    std::vector<SpellSample> precastShadowLowSounds_;
+    std::vector<SpellSample> precastShadowMediumSounds_;
+    std::vector<SpellSample> precastShadowHighSounds_;
+    std::vector<SpellSample> precastArcaneSounds_;
+
+    // Cast sound libraries (spell release)
+    std::vector<SpellSample> castFireSounds_;
+    std::vector<SpellSample> castFrostSounds_;
+    std::vector<SpellSample> castHolySounds_;
+    std::vector<SpellSample> castNatureSounds_;
+    std::vector<SpellSample> castShadowSounds_;
+
+    // Impact sound libraries (spell hits)
+    std::vector<SpellSample> impactFireballSounds_;
+    std::vector<SpellSample> impactBlizzardSounds_;
+    std::vector<SpellSample> impactHolySounds_;
+    std::vector<SpellSample> impactArcaneMissileSounds_;
+
+    // State tracking
+    float volumeScale_ = 1.0f;
+    bool initialized_ = false;
+
+    // Helper methods
+    bool loadSound(const std::string& path, SpellSample& sample, pipeline::AssetManager* assets);
+    void playSound(const std::vector<SpellSample>& library, float volumeMultiplier = 1.0f);
+    void playRandomSound(const std::vector<SpellSample>& library, float volumeMultiplier = 1.0f);
+};
+
+} // namespace audio
+} // namespace wowee