feat(custom-rulesets): support custom rulesets (#23)

* feat(custom_ruleset): add custom rulesets support

* feat(custom-ruleset): add version check

* feat(custom-ruleset): add LegacyIO API to get ruleset hashes

* feat(pp): add check for rulesets whose pp cannot be calculated

* docs(readme): update README to include support for custom rulesets

* fix(custom-ruleset): make `rulesets` empty instead of throw a error when version check is disabled

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* chore(custom-ruleset): apply the latest changes of generator

c891bcd159

and

e25041ad3b

* feat(calculator): add fallback performance calculation for unsupported modes

* fix(calculator): remove debug print

* fix: resolve reviews

* feat(calculator): add difficulty calculation checks

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

app/database/playlists.py

@@ -28,7 +28,7 @@ if TYPE_CHECKING:
 class PlaylistBase(SQLModel, UTCBaseModel):
     id: int = Field(index=True)
     owner_id: int = Field(sa_column=Column(BigInteger, ForeignKey("lazer_users.id")))
-    ruleset_id: int = Field(ge=0, le=3)
+    ruleset_id: int
     expired: bool = Field(default=False)
     playlist_order: int = Field(default=0)
     played_at: datetime | None = Field(