Add spin session functionality and update game mechanics

- Introduced a new `spin_sessions` table to track user spin activities.
- Updated the API to include a new endpoint for spinning games, allowing users to place bets and specify spin counts.
- Enhanced game information structure and added validation for bets and spin counts.
- Implemented the `Forest Fortune` slot game mechanics, including payline evaluation and scatter functionality.
- Updated dependencies in `pyproject.toml` for development and added `httpx` for HTTP requests.
- Added unit tests for the new slot mechanics and API endpoints to ensure functionality and reliability.

app/slots/coming_soon.py

@@ -0,0 +1,29 @@
+from __future__ import annotations
+
+from decimal import Decimal
+
+from app.slots.base import BaseSlot
+from app.slots.rng import Rng
+from app.slots.types import Grid, SessionMetaState, SpinOutcome
+
+
+class ComingSoonSlot(BaseSlot):
+    status = "coming_soon"
+    min_bet = Decimal("1.00")
+    max_bet = Decimal("100.00")
+    min_spin_count = 1
+    max_spin_count = 1
+
+    def __init__(self, slug: str, title: str, description: str) -> None:
+        self.slug = slug
+        self.title = title
+        self.description = description
+
+    def build_grid(self, rng: Rng) -> Grid:
+        raise RuntimeError(f"Game '{self.slug}' is not available")
+
+    def evaluate(self, grid: Grid, bet: Decimal, multiplier: int) -> SpinOutcome:
+        raise RuntimeError(f"Game '{self.slug}' is not available")
+
+    def session_meta_on_spin(self, state: SessionMetaState, outcome: SpinOutcome) -> SessionMetaState:
+        return state