feat: Implement payment notification system and API structure

- Added notifications for successful payments in `api/core/notifications.py`.
- Created main API entry point in `api/main.py` with FastAPI integration.
- Established routing structure in `api/routes/__init__.py` and `api/routes/pally.py` for handling payment callbacks.
- Developed billing handlers in `bot/handlers/billing.py` and `bot/handlers/buy.py` for subscription management.
- Introduced state management for user interactions in `bot/states/`.
- Created user interface elements in `bot/keyboards/` for navigation and payment processing.
- Set up middleware for dependency injection in `bot/middlewares/di.py`.
- Added support for user commands and interactions in `bot/handlers/common.py` and `bot/handlers/support.py`.
- Implemented logging and error handling throughout the bot's functionality.
- Created entry point script for API server in `entrypoints/api.sh`.

Dockerfile.api

@@ -0,0 +1,41 @@
+# Stage 1: Builder - Install dependencies
+FROM python:3.13-slim AS builder
+
+WORKDIR /build
+
+# Install build-time dependencies required for compiling packages like asyncpg
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    libpq-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir --prefix=/install -r requirements.txt
+
+# Stage 2: Runner - Final lightweight image
+FROM python:3.13-slim AS runner
+
+ENV PYTHONUNBUFFERED=1 \
+    PYTHONDONTWRITEBYTECODE=1
+
+WORKDIR /app
+
+# Install runtime dependencies required by asyncpg
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libpq5 \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy installed Python packages from the builder stage
+COPY --from=builder /install /usr/local
+
+# Copy application source code
+COPY . .
+
+RUN sed -i 's/\r$//' ./entrypoints/api.sh && \
+    chmod +x ./entrypoints/api.sh
+
+# Ensure the api script is executable
+RUN chmod +x ./entrypoints/api.sh
+
+# Default command runs migrations and starts the API
+CMD ["sh", "./entrypoints/api.sh"]