Play single shot sound for spread bullets

[jackandcarter]

Motivation

• Prevent spread (multi-bullet) power-ups from playing the bullet SFX once per spawned bullet which causes amplified/unnatural audio.
• Preserve the existing rapid-fire / machine-gun audio behavior, which is a separate mechanic and should remain unchanged.
• Ensure bullet ownership and debug logging remain intact when changing how and when sounds are played.

Description

• Add a playSound parameter to SpawnBullet and return a bool indicating whether a bullet was spawned via SpawnBullet(..., playSound).
• For single-bullet shots call SpawnBullet(..., playSound: true) so per-shot audio is preserved for normal fire.
• For spread (count > 1) suppress per-bullet SFX (playSound: false) and play a single AudioManager.Instance.PlaySoundEffect(AudioManager.Instance.playerBulletSound) if any bullet was spawned.
• Retain bulletComponent.ownerPlayerIndex assignment and existing debug logging when a bullet is spawned.

Testing

• No automated tests were run.
• Local compile checks were performed as part of development (no runtime tests executed).
• Manual review ensured sound is emitted once for spread volleys and still per-shot for single bullets.

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Codex Task