feat: impl docs (#4)

The entire public api is covered with documentation in two languages - Russian and English.

the library now supports the latest three versions of python - 3.12, 3.13 and 3.14

minor design changes: now, when a Boolean flag is entered, its value is an empty string, not None.

tests have been adapted to the supported versions of python, readmi has been redesigned in two languages, German is no longer available.

docs/code_snippets/quickstart/calculator_app.py

@@ -0,0 +1,68 @@
+import operator
+import re
+
+from argenta import App, Orchestrator, Response, Router
+from argenta.app import DynamicDividingLine
+from argenta.command import Command, Flag, Flags
+from argenta.response.status import ResponseStatus
+
+router = Router("Calculator")
+
+operations = {
+    'mul': operator.mul,
+    'sub': operator.sub,
+    'add': operator.add
+}
+
+@router.command(
+    Command(
+        "calc",
+        description="Calculator with two numbers",
+        flags=Flags(
+            [
+                Flag("a", possible_values=re.compile(r"^\d{,5}$")),  # First number
+                Flag("b", possible_values=re.compile(r"^\d{,5}$")),  # Second number
+                Flag("operation", possible_values=["add", "sub", "mul"]),  # Operation: add, sub, mul
+            ]
+        ),
+    )
+)
+def calc_handler(response: Response):
+    # Get flag values
+    a_flag = response.input_flags.get_flag_by_name("a")
+    b_flag = response.input_flags.get_flag_by_name("b")
+    op_flag = response.input_flags.get_flag_by_name("op")
+
+    # Check that all flags are provided
+    if response.status != ResponseStatus.ALL_FLAGS_VALID or not all([a_flag, b_flag, op_flag]):
+        print("Error: must specify --a, --b and --op")
+        return
+
+    a = float(a_flag.input_value)
+    b = float(b_flag.input_value)
+    operation = op_flag.input_value
+
+    try:
+        result = operations[operation](a, b)
+    except ZeroDivisionError:
+        print("Can't divide by zero")
+    else:
+        print(f"Result: {result}")
+
+
+app = App(
+    initial_message="Calculator",
+    repeat_command_groups_printing=False,
+    prompt=">> ",
+    dividing_line=DynamicDividingLine("~"),
+)
+orchestrator = Orchestrator()
+
+
+def main():
+    app.include_router(router)
+    orchestrator.start_polling(app)
+
+
+if __name__ == "__main__":
+    main()