Release v0.9.75 runtime and onboarding update

Ship the 0.9.75 source update with improved startup/runtime hardening, operator API key onboarding, Meshtastic MQTT controls, Infonet/MeshChat separation, desktop package versioning, and aircraft telemetry refinements.

Also updates focused backend/frontend tests for node settings, Meshtastic MQTT settings, and desktop runtime behavior.

backend/tests/mesh/test_node_settings.py

@@ -7,9 +7,44 @@ def test_node_settings_roundtrip(tmp_path, monkeypatch):
     monkeypatch.setattr(node_settings, "_cache_ts", 0.0)
 
     initial = node_settings.read_node_settings()
+    disabled = node_settings.write_node_settings(enabled=False)
     updated = node_settings.write_node_settings(enabled=True)
     reread = node_settings.read_node_settings()
 
-    assert initial["enabled"] is False
+    assert initial["enabled"] is True
+    assert initial["operator_disabled"] is False
+    assert disabled["enabled"] is False
+    assert disabled["operator_disabled"] is True
     assert updated["enabled"] is True
+    assert updated["operator_disabled"] is False
     assert reread["enabled"] is True
+
+
+def test_legacy_disabled_node_settings_auto_enable(tmp_path, monkeypatch):
+    from services import node_settings
+
+    settings_path = tmp_path / "node.json"
+    settings_path.write_text('{"enabled": false, "updated_at": 123}', encoding="utf-8")
+    monkeypatch.setattr(node_settings, "NODE_FILE", settings_path)
+    monkeypatch.setattr(node_settings, "_cache", None)
+    monkeypatch.setattr(node_settings, "_cache_ts", 0.0)
+
+    reread = node_settings.read_node_settings()
+
+    assert reread["enabled"] is True
+    assert reread["operator_disabled"] is False
+
+
+def test_explicit_operator_disabled_stays_disabled(tmp_path, monkeypatch):
+    from services import node_settings
+
+    settings_path = tmp_path / "node.json"
+    settings_path.write_text('{"enabled": false, "operator_disabled": true, "updated_at": 123}', encoding="utf-8")
+    monkeypatch.setattr(node_settings, "NODE_FILE", settings_path)
+    monkeypatch.setattr(node_settings, "_cache", None)
+    monkeypatch.setattr(node_settings, "_cache_ts", 0.0)
+
+    reread = node_settings.read_node_settings()
+
+    assert reread["enabled"] is False
+    assert reread["operator_disabled"] is True