feat: add team calendar ICS endpoint and related functionality

- Implemented a new API endpoint to generate an ICS calendar for team duty shifts, accessible via a valid token.
- Enhanced the `calendar_link` command to return both personal and team calendar URLs.
- Added a new function to build the team ICS file, ensuring each event includes the duty holder's name in the description.
- Updated tests to cover the new team calendar functionality, including validation for token formats and response content.
- Revised internationalization messages to reflect the new team calendar links.

tests/test_handlers_commands.py

@@ -202,7 +202,7 @@ async def test_set_phone_result_error_replies_error():
 
 @pytest.mark.asyncio
 async def test_calendar_link_with_user_and_token_replies_with_url():
-    """calendar_link with allowed user and token -> reply with link."""
+    """calendar_link with allowed user and token -> reply with personal and team URLs."""
     message = MagicMock()
     message.reply_text = AsyncMock()
     user = _make_user()
@@ -233,14 +233,15 @@ async def test_calendar_link_with_user_and_token_replies_with_url():
                         ):
                             with patch("duty_teller.handlers.commands.t") as mock_t:
                                 mock_t.side_effect = lambda lang, key, **kw: (
-                                    f"URL: {kw.get('url', '')}"
+                                    f"Personal: {kw.get('url_personal', '')} Team: {kw.get('url_team', '')}"
                                     if "success" in key
                                     else "Hint"
                                 )
                                 await calendar_link(update, MagicMock())
     message.reply_text.assert_called_once()
     call_args = message.reply_text.call_args[0][0]
-    assert "abc43token" in call_args or "example.com" in call_args
+    assert "/api/calendar/ical/abc43token.ics" in call_args
+    assert "/api/calendar/ical/team/abc43token.ics" in call_args
 
 
 @pytest.mark.asyncio