fix(subscriptions): use x-api-key connectionParams format for WebSocket auth

The Unraid graphql-ws server expects the API key directly in connectionParams
as `x-api-key`, not nested under `headers`. The old format caused the server
to fall through to cookie auth and crash on `undefined.csrf_token`.

Fixed in snapshot.py (×2), manager.py, diagnostics.py, and updated the
integration test assertion to match the correct payload shape.

.gitignore

@@ -10,6 +10,9 @@ wheels/
 # Tool artifacts (pytest, ruff, ty, coverage all write here)
 .cache/
 
+# Hypothesis example database (machine-local, auto-regenerated)
+.hypothesis/
+
 # Legacy artifact locations (in case tools run outside pyproject config)
 .pytest_cache/
 .ruff_cache/