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/test_dashboard_stats.py

@@ -0,0 +1,58 @@
+"""Dashboard inventory statistics."""
+
+from __future__ import annotations
+
+from datetime import UTC, datetime
+
+from shelly_manager.core.models import ShellyDevice
+from shelly_manager.ui.dashboard_stats import compute_inventory_stats
+
+
+def _d(
+    i: str,
+    *,
+    gen: int = 2,
+    online: bool = True,
+    auth: bool = False,
+    model: str = "SNSW-001P16EU",
+    caps: list[str] | None = None,
+    tags: list[str] | None = None,
+) -> ShellyDevice:
+    return ShellyDevice(
+        id=i,
+        name=None,
+        mac=f"AA:BB:CC:DD:EE:{i[:2]}",
+        ip=f"192.168.1.{i}",
+        generation=gen,  # type: ignore[arg-type]
+        model=model,
+        firmware="1",
+        online=online,
+        last_seen=datetime.now(UTC),
+        capabilities=caps or [],
+        status={"sys": {"restart_required": False}},
+        settings={},
+        tags=tags or [],
+        auth_required=auth,
+    )
+
+
+def test_compute_inventory_stats_empty() -> None:
+    s = compute_inventory_stats([])
+    assert s.total == 0
+    assert s.online == 0
+
+
+def test_compute_inventory_stats_mix() -> None:
+    devices = [
+        _d("01", gen=1, online=True, model="SHSW-1"),
+        _d("02", gen=2, online=False, tags=["floor1"]),
+        _d("03", gen=3, caps=["switch", "meter"]),
+    ]
+    s = compute_inventory_stats(devices)
+    assert s.total == 3
+    assert s.online == 2
+    assert s.offline == 1
+    assert s.gen1 == 1 and s.gen2 == 1 and s.gen3 == 1
+    assert s.devices_with_tags == 1
+    assert s.unique_tag_labels == 1
+    assert len(s.top_models) >= 2