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/flags/deploy_handler.py

@@ -0,0 +1,24 @@
+from argenta import Router, Response
+from argenta.command import Command, Flag, PossibleValues
+from argenta.command.flag import ValidationStatus
+
+router = Router()
+
+
+@router.command(Command(
+    "deploy", 
+    flags=Flag("verbose", possible_values=PossibleValues.NEITHER)
+))
+def deploy_handler(response: Response):
+    # Check for toggle flag presence
+    verbose_flag = response.input_flags.get_flag_by_name("verbose")
+
+    if verbose_flag and verbose_flag.status == ValidationStatus.VALID:
+        print("Deploying with verbose output...")
+        # Detailed logic
+    elif verbose_flag and verbose_flag.status == ValidationStatus.INVALID:
+        print("Incorrect flag value")
+        return
+    else:
+        print("Deploying...")
+        # Normal logic