Refactor project structure and enhance Docker configuration

- Updated `.dockerignore` to exclude test and development artifacts, optimizing the Docker image size.
- Refactored `main.py` to delegate execution to `duty_teller.run.main()`, simplifying the entry point.
- Introduced a new `duty_teller` package to encapsulate core functionality, improving modularity and organization.
- Enhanced `pyproject.toml` to define a script for running the application, streamlining the execution process.
- Updated README documentation to reflect changes in project structure and usage instructions.
- Improved Alembic environment configuration to utilize the new package structure for database migrations.

tests/helpers.py

@@ -0,0 +1,33 @@
+"""Shared test helpers (e.g. make_init_data for Telegram auth tests)."""
+
+import hashlib
+import hmac
+import json
+from urllib.parse import quote, unquote
+
+
+def make_init_data(
+    user: dict | None,
+    bot_token: str,
+    auth_date: int | None = None,
+) -> str:
+    """Build initData string with valid HMAC for testing."""
+    params = {}
+    if user is not None:
+        params["user"] = quote(json.dumps(user))
+    if auth_date is not None:
+        params["auth_date"] = str(auth_date)
+    pairs = sorted(params.items())
+    data_string = "\n".join(f"{k}={unquote(v)}" for k, v in pairs)
+    secret_key = hmac.new(
+        b"WebAppData",
+        msg=bot_token.encode(),
+        digestmod=hashlib.sha256,
+    ).digest()
+    computed = hmac.new(
+        secret_key,
+        msg=data_string.encode(),
+        digestmod=hashlib.sha256,
+    ).hexdigest()
+    params["hash"] = computed
+    return "&".join(f"{k}={v}" for k, v in sorted(params.items()))