Initial commit: Shelly Manager with Textual CLI, Streamlit UI, and comprehensive .gitignore

Shelly device management app with mDNS/subnet discovery, inventory,
configuration, and mass operations for Gen1/Gen2+ devices.

Includes .gitignore excluding runtime data (device DB, user config),
AI conversation history, build artifacts, and common Python/OS patterns.

tests/integration/conftest.py

@@ -0,0 +1,35 @@
+"""Integration test configuration."""
+
+from __future__ import annotations
+
+import os
+
+import pytest
+
+
+def integration_enabled() -> bool:
+    return os.environ.get("SHELLY_INTEGRATION", "").strip().lower() in (
+        "1",
+        "true",
+        "yes",
+        "on",
+    )
+
+
+def mdns_timeout_sec() -> float:
+    raw = os.environ.get("SHELLY_MDNS_SECONDS", "6")
+    try:
+        return max(2.0, float(raw))
+    except ValueError:
+        return 6.0
+
+
+def subnet_cidr() -> str | None:
+    c = os.environ.get("SHELLY_SUBNET", "").strip()
+    return c or None
+
+
+requires_integration = pytest.mark.skipif(
+    not integration_enabled(),
+    reason="Set SHELLY_INTEGRATION=1 to run LAN tests (see README).",
+)