fix(bot): Telegram through TG_PROXY_URL — docker on the RF server has no IPv4 route to Telegram

Closes #108

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_telegram_proxy.py

@@ -0,0 +1,16 @@
+"""TG_PROXY_URL: the bot session goes through the proxy when it is set."""
+
+from app.channels import telegram
+from app.config import get_settings
+
+TOKEN = "123456:" + "A" * 35
+
+
+def test_make_bot_without_proxy(monkeypatch):
+    monkeypatch.setattr(get_settings(), "tg_proxy_url", "")
+    assert telegram.make_bot(TOKEN).session.proxy is None
+
+
+def test_make_bot_with_proxy(monkeypatch):
+    monkeypatch.setattr(get_settings(), "tg_proxy_url", "http://user:pass@127.0.0.1:8888")
+    assert telegram.make_bot(TOKEN).session.proxy == "http://user:pass@127.0.0.1:8888"