v2.26.11: fix APRS map ignoring configured observer position (#193)

The APRS map initialisation only checked for a live GPS fix, falling
back to the centre of the US (39.8N, 98.6W) when none was available.
It never read the observer position configured in .env via
INTERCEPT_DEFAULT_LAT / INTERCEPT_DEFAULT_LON.

Seed aprsUserLocation from ObserverLocation.getShared() (or the
Jinja-injected defaults) on page load so the map centres on the
user's configured position and distance calculations work without GPS.

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

config.py

@@ -7,15 +7,15 @@ import os
 import sys
 
 # Application version
-VERSION = "2.26.10"
+VERSION = "2.26.11"
 
 # Changelog - latest release notes (shown on welcome screen)
 CHANGELOG = [
     {
-        "version": "2.26.10",
+        "version": "2.26.11",
         "date": "March 2026",
         "highlights": [
-            "Fix APRS stop timeout and inverted SDR device status",
+            "APRS map now centres on configured observer position from .env",
         ]
     },
     {