feat: ADS-B historical playback map (closes #208)

- New GET /adsb/history/playback endpoint returns time-bucketed snapshots
  (one position per aircraft per N-second bucket) via a SQL window function
- Playback tab added to adsb_history.html: Leaflet map with animated
  aircraft markers, play/pause, 1x–20x speed, scrubber, and time display
- Configurable window (15 min – 24 h) and bucket step (10 s – 5 min)
- Requires the history Docker profile or INTERCEPT_ADSB_HISTORY_ENABLED=true
- Bump version to 2.32.0

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

config.py

@@ -7,10 +7,17 @@ import os
 import sys
 
 # Application version
-VERSION = "2.31.0"
+VERSION = "2.32.0"
 
 # Changelog - latest release notes (shown on welcome screen)
 CHANGELOG = [
+    {
+        "version": "2.32.0",
+        "date": "July 2026",
+        "highlights": [
+            "Feat: ADS-B historical playback — replay past aircraft positions on an interactive map with play/pause, speed control, and time scrubber (requires history profile)",
+        ],
+    },
     {
         "version": "2.31.0",
         "date": "July 2026",