Add DMR digital voice, WebSDR, and listening post enhancements

- DMR/P25 digital voice decoder mode with DSD-FME integration
- WebSDR mode with KiwiSDR audio proxy and websocket-client support
- Listening post waterfall/spectrogram visualization and audio streaming
- Dockerfile updates for mbelib and DSD-FME build dependencies
- New tests for DMR, WebSDR, KiwiSDR, waterfall, and signal guess API
- Chart.js date adapter for time-scale axes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_signal_guess_api.py

@@ -0,0 +1,100 @@
+"""Tests for the Signal Identification (guess) API endpoint."""
+
+import pytest
+
+
+@pytest.fixture
+def auth_client(client):
+    """Client with logged-in session."""
+    with client.session_transaction() as sess:
+        sess['logged_in'] = True
+    return client
+
+
+def test_signal_guess_fm_broadcast(auth_client):
+    """FM broadcast frequency should return a known signal type."""
+    resp = auth_client.post('/listening/signal/guess', json={
+        'frequency_mhz': 98.1,
+        'modulation': 'wfm',
+    })
+    assert resp.status_code == 200
+    data = resp.get_json()
+    assert data['status'] == 'ok'
+    assert data['primary_label']
+    assert data['confidence'] in ('HIGH', 'MEDIUM', 'LOW')
+
+
+def test_signal_guess_airband(auth_client):
+    """Airband frequency should be identified."""
+    resp = auth_client.post('/listening/signal/guess', json={
+        'frequency_mhz': 121.5,
+        'modulation': 'am',
+    })
+    assert resp.status_code == 200
+    data = resp.get_json()
+    assert data['status'] == 'ok'
+    assert data['primary_label']
+
+
+def test_signal_guess_ism_band(auth_client):
+    """ISM band frequency (433.92 MHz) should be identified."""
+    resp = auth_client.post('/listening/signal/guess', json={
+        'frequency_mhz': 433.92,
+    })
+    assert resp.status_code == 200
+    data = resp.get_json()
+    assert data['status'] == 'ok'
+    assert data['primary_label']
+    assert data['confidence'] in ('HIGH', 'MEDIUM', 'LOW')
+
+
+def test_signal_guess_missing_frequency(auth_client):
+    """Missing frequency should return 400."""
+    resp = auth_client.post('/listening/signal/guess', json={})
+    assert resp.status_code == 400
+    data = resp.get_json()
+    assert data['status'] == 'error'
+
+
+def test_signal_guess_invalid_frequency(auth_client):
+    """Invalid frequency value should return 400."""
+    resp = auth_client.post('/listening/signal/guess', json={
+        'frequency_mhz': 'abc',
+    })
+    assert resp.status_code == 400
+
+
+def test_signal_guess_negative_frequency(auth_client):
+    """Negative frequency should return 400."""
+    resp = auth_client.post('/listening/signal/guess', json={
+        'frequency_mhz': -5.0,
+    })
+    assert resp.status_code == 400
+
+
+def test_signal_guess_with_region(auth_client):
+    """Specifying region should work."""
+    resp = auth_client.post('/listening/signal/guess', json={
+        'frequency_mhz': 462.5625,
+        'region': 'US',
+    })
+    assert resp.status_code == 200
+    data = resp.get_json()
+    assert data['status'] == 'ok'
+
+
+def test_signal_guess_response_structure(auth_client):
+    """Response should have all expected fields."""
+    resp = auth_client.post('/listening/signal/guess', json={
+        'frequency_mhz': 146.52,
+        'modulation': 'fm',
+    })
+    assert resp.status_code == 200
+    data = resp.get_json()
+    assert 'primary_label' in data
+    assert 'confidence' in data
+    assert 'alternatives' in data
+    assert 'explanation' in data
+    assert 'tags' in data
+    assert isinstance(data['alternatives'], list)
+    assert isinstance(data['tags'], list)