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_kiwisdr.py

@@ -1,21 +1,18 @@
 """Tests for the KiwiSDR WebSocket audio client."""
 
 import struct
-from unittest.mock import patch, MagicMock
-
-import pytest
+from unittest.mock import MagicMock, patch
 
 from utils.kiwisdr import (
-    KiwiSDRClient,
+    KIWI_DEFAULT_PORT,
     KIWI_SAMPLE_RATE,
     KIWI_SND_HEADER_SIZE,
-    KIWI_DEFAULT_PORT,
     MODE_FILTERS,
     VALID_MODES,
+    KiwiSDRClient,
     parse_host_port,
 )
 
-
 # ============================================
 # parse_host_port tests
 # ============================================