test(conftest): mute Telegram in all tests to stop prod leakage

A pytest run on prod was sending REAL Telegram messages to Slava: some tests
(e.g. test_webhook_dedup advancing a stage) reach notify_stage_change ->
send_telegram, which read the live .env token/chat_id and actually POSTed.

Add an autouse fixture stubbing send_telegram to a no-op for every test. Patch
the SOURCE src.notifications.send_telegram (covers all notify_* helpers and the
many modules that do a local from .notifications import send_telegram inside
functions) AND src.stage_engine.send_telegram (module-level binding, would not be
intercepted by the source patch alone). webhooks/plane, launcher, queue_worker are
patched defensively with raising=False.

Verified: full suite run with FAKE telegram creds + an un-swallowable httpx.post
trip-wire (BaseException, so send_telegram except Exception can not hide it) shows
ZERO calls to api.telegram.org. Without the fixture the trip-wire fires, proving
the guard is real.

tests/conftest.py

@@ -0,0 +1,40 @@
+"""Global pytest fixtures.
+
+test(conftest): mute Telegram in ALL tests to stop prod leakage.
+
+Background: a pytest run on prod was sending REAL Telegram messages to Slava,
+because some tests (e.g. test_webhook_dedup advancing a stage) reach
+notify_stage_change -> send_telegram, which reads the live .env
+telegram_bot_token/chat_id and actually POSTs to Telegram.
+
+This autouse fixture stubs send_telegram to a no-op for every test:
+
+  - "src.notifications.send_telegram" is the SOURCE. All the notify_* helpers in
+    notifications.py call the module-global send_telegram, and every other module
+    that does a *local* `from .notifications import send_telegram` inside a
+    function resolves it live at call time -> covered by patching the source.
+
+  - "src.stage_engine.send_telegram" is patched too, because stage_engine binds
+    send_telegram as a MODULE-LEVEL name (from .notifications import send_telegram
+    at import), so a patch of the source alone would not intercept its 3 direct
+    calls. webhooks/plane and launcher import it locally inside functions, so the
+    source patch already covers them; they are patched defensively with
+    raising=False anyway in case that ever changes.
+
+raising=False so a module that doesn't (yet) expose the name never breaks setup.
+"""
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def _no_telegram(monkeypatch):
+    _noop = lambda *a, **k: None  # noqa: E731
+    # Source of truth (covers notifications.notify_* and all local re-imports).
+    monkeypatch.setattr("src.notifications.send_telegram", _noop, raising=False)
+    # Module-level binding in stage_engine (and defensive coverage elsewhere).
+    monkeypatch.setattr("src.stage_engine.send_telegram", _noop, raising=False)
+    monkeypatch.setattr("src.webhooks.plane.send_telegram", _noop, raising=False)
+    monkeypatch.setattr("src.agents.launcher.send_telegram", _noop, raising=False)
+    monkeypatch.setattr("src.queue_worker.send_telegram", _noop, raising=False)
+    yield