fix(cli): reject --telegram combined with other channel flags (#743)

Telegram is the legacy pairing-only mode; combining it with
--discord/--slack/--whatsapp/etc produced confusing startup state where
the dashboard never came up but the extra channels silently ran. Fail
fast via argparse error so the user gets a clear message.

Uses `getattr(args, flag, False)` so unregistered flags don't crash.
Leaves `_check_extras_installed` and the rest of the main() control
flow untouched (earlier iterations of the PR moved it too early and
broke `doctor`/`status`).

Reduces the original test to the conflict cases only — asserting on the
non-conflict path would require mocking the full startup pipeline.

Co-Authored-By: Aravindavenge <119057955+Aravindavenge@users.noreply.github.com>

src/pocketpaw/__main__.py

@@ -424,6 +424,14 @@ def main() -> None:
     args = parser.parse_args()
     _resolve_subargs(args)
 
+    # Reject combining --telegram with other channel flags. Telegram is the
+    # legacy pairing-only path; other channels require the dashboard.
+    _other_channel_flags = ("discord", "slack", "whatsapp", "signal", "matrix", "teams", "gchat")
+    if getattr(args, "telegram", False) and any(
+        getattr(args, f, False) for f in _other_channel_flags
+    ):
+        parser.error("--telegram cannot be combined with other channel flags")
+
     # ── Early-exit commands (no settings, health, or env setup needed) ──
     if args.command in _EARLY_COMMANDS:
         exit_code = _handle_early_command(args)

tests/test_cli_flags.py

@@ -0,0 +1,16 @@
+"""Tests for CLI flag validation in pocketpaw.__main__."""
+
+from __future__ import annotations
+
+import pytest
+
+
+@pytest.mark.parametrize("conflict_flag", ["--discord", "--slack", "--whatsapp"])
+def test_telegram_conflicts_with_other_channel_flag(monkeypatch, conflict_flag):
+    """--telegram combined with another channel flag must exit via argparse error (code 2)."""
+    from pocketpaw.__main__ import main
+
+    monkeypatch.setattr("sys.argv", ["pocketpaw", "--telegram", conflict_flag])
+    with pytest.raises(SystemExit) as exc_info:
+        main()
+    assert exc_info.value.code == 2