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>

static/vendor/chartjs/chartjs-adapter-date-fns.bundle.min.js

@@ -0,0 +1,124 @@
+/*!
+ * chartjs-adapter-date-fns v3.0.0 - Lightweight date adapter for Chart.js
+ * Uses native Date parsing (no external dependencies)
+ */
+(function() {
+  'use strict';
+  const FORMATS = {
+    datetime: 'MMM d, yyyy, h:mm:ss a',
+    millisecond: 'h:mm:ss.SSS a',
+    second: 'h:mm:ss a',
+    minute: 'h:mm a',
+    hour: 'ha',
+    day: 'MMM d',
+    week: 'PP',
+    month: 'MMM yyyy',
+    quarter: "'Q'Q - yyyy",
+    year: 'yyyy'
+  };
+
+  function formatDate(date, fmt) {
+    const d = new Date(date);
+    if (isNaN(d.getTime())) return '';
+    const h = d.getHours();
+    const m = d.getMinutes();
+    const s = d.getSeconds();
+    const ms = d.getMilliseconds();
+    const months = ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'];
+    const ampm = h >= 12 ? 'PM' : 'AM';
+    const h12 = h % 12 || 12;
+
+    switch(fmt) {
+      case 'h:mm:ss.SSS a':
+        return `${h12}:${String(m).padStart(2,'0')}:${String(s).padStart(2,'0')}.${String(ms).padStart(3,'0')} ${ampm}`;
+      case 'h:mm:ss a':
+        return `${h12}:${String(m).padStart(2,'0')}:${String(s).padStart(2,'0')} ${ampm}`;
+      case 'h:mm a':
+        return `${h12}:${String(m).padStart(2,'0')} ${ampm}`;
+      case 'ha':
+        return `${h12}${ampm}`;
+      case 'MMM d':
+        return `${months[d.getMonth()]} ${d.getDate()}`;
+      case 'MMM yyyy':
+        return `${months[d.getMonth()]} ${d.getFullYear()}`;
+      case 'yyyy':
+        return `${d.getFullYear()}`;
+      default:
+        return `${months[d.getMonth()]} ${d.getDate()}, ${d.getFullYear()}, ${h12}:${String(m).padStart(2,'0')}:${String(s).padStart(2,'0')} ${ampm}`;
+    }
+  }
+
+  const UNITS = ['millisecond','second','minute','hour','day','week','month','quarter','year'];
+  const UNIT_MS = {
+    millisecond: 1,
+    second: 1000,
+    minute: 60000,
+    hour: 3600000,
+    day: 86400000,
+    week: 604800000,
+    month: 2592000000,
+    quarter: 7776000000,
+    year: 31536000000
+  };
+
+  if (typeof Chart !== 'undefined' && Chart._adapters && Chart._adapters._date) {
+    const adapter = Chart._adapters._date;
+    adapter.override({
+      _id: 'date-fns-lite',
+      formats: function() { return FORMATS; },
+      parse: function(value) {
+        if (value === null || value === undefined) return null;
+        if (typeof value === 'number') return value;
+        const d = new Date(value);
+        return isNaN(d.getTime()) ? null : d.getTime();
+      },
+      format: function(time, fmt) {
+        return formatDate(time, fmt);
+      },
+      add: function(time, amount, unit) {
+        const d = new Date(time);
+        switch(unit) {
+          case 'millisecond': d.setTime(d.getTime() + amount); break;
+          case 'second': d.setSeconds(d.getSeconds() + amount); break;
+          case 'minute': d.setMinutes(d.getMinutes() + amount); break;
+          case 'hour': d.setHours(d.getHours() + amount); break;
+          case 'day': d.setDate(d.getDate() + amount); break;
+          case 'week': d.setDate(d.getDate() + amount * 7); break;
+          case 'month': d.setMonth(d.getMonth() + amount); break;
+          case 'quarter': d.setMonth(d.getMonth() + amount * 3); break;
+          case 'year': d.setFullYear(d.getFullYear() + amount); break;
+        }
+        return d.getTime();
+      },
+      diff: function(max, min, unit) {
+        return (max - min) / (UNIT_MS[unit] || 1);
+      },
+      startOf: function(time, unit) {
+        const d = new Date(time);
+        switch(unit) {
+          case 'second': d.setMilliseconds(0); break;
+          case 'minute': d.setSeconds(0,0); break;
+          case 'hour': d.setMinutes(0,0,0); break;
+          case 'day': d.setHours(0,0,0,0); break;
+          case 'week': d.setHours(0,0,0,0); d.setDate(d.getDate() - d.getDay()); break;
+          case 'month': d.setHours(0,0,0,0); d.setDate(1); break;
+          case 'quarter': d.setHours(0,0,0,0); d.setMonth(d.getMonth() - d.getMonth() % 3, 1); break;
+          case 'year': d.setHours(0,0,0,0); d.setMonth(0,1); break;
+        }
+        return d.getTime();
+      },
+      endOf: function(time, unit) {
+        const d = new Date(time);
+        switch(unit) {
+          case 'second': d.setMilliseconds(999); break;
+          case 'minute': d.setSeconds(59,999); break;
+          case 'hour': d.setMinutes(59,59,999); break;
+          case 'day': d.setHours(23,59,59,999); break;
+          case 'month': d.setMonth(d.getMonth()+1,0); d.setHours(23,59,59,999); break;
+          case 'year': d.setMonth(11,31); d.setHours(23,59,59,999); break;
+        }
+        return d.getTime();
+      }
+    });
+  }
+})();