v2.26.0: fix SSE fanout crash and branded logo FOUC

- Fix SSE fanout thread AttributeError when source queue is None during
  interpreter shutdown by snapshotting to local variable with null guard
- Fix branded "i" logo rendering oversized on first page load (FOUC) by
  adding inline width/height to SVG elements across 10 templates
- Bump version to 2.26.0 in config.py, pyproject.toml, and CHANGELOG.md

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

tests/test_bluetooth_api.py

@@ -1,13 +1,13 @@
 """API endpoint tests for Bluetooth v2 routes."""
 
-import pytest
-import json
-from unittest.mock import MagicMock, patch, PropertyMock
 from datetime import datetime
+from unittest.mock import MagicMock, patch
+
+import pytest
 from flask import Flask
 
 from routes.bluetooth_v2 import bluetooth_v2_bp
-from utils.bluetooth.models import BTDeviceAggregate, ScanStatus, SystemCapabilities
+from utils.bluetooth.models import BTDeviceAggregate, SystemCapabilities
 
 
 @pytest.fixture