feat: Add unique constraint on sound hash and update related tests

app/models/sound.py

@@ -1,6 +1,6 @@
 from typing import TYPE_CHECKING
 
-from sqlmodel import Field, Relationship
+from sqlmodel import Field, Relationship, UniqueConstraint
 
 from app.models.base import BaseModel
 
@@ -29,6 +29,11 @@ class Sound(BaseModel, table=True):
     is_music: bool = Field(default=False, nullable=False)
     is_deletable: bool = Field(default=True, nullable=False)
 
+    # constraints
+    __table_args__ = (
+        UniqueConstraint("hash", name="uq_sound_hash"),
+    )
+
     # relationships
     playlist_sounds: list["PlaylistSound"] = Relationship(back_populates="sound")
     extractions: list["Extraction"] = Relationship(back_populates="sound")