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_meshtastic.py

@@ -9,10 +9,10 @@ Tests cover:
 """
 
 import json
-import pytest
-from unittest.mock import Mock, patch, MagicMock
 from datetime import datetime, timezone
+from unittest.mock import Mock, patch
 
+import pytest
 
 # =============================================================================
 # Utility Module Tests
@@ -173,9 +173,10 @@ class TestPSKParsing:
 
     def test_parse_psk_base64(self):
         """Should decode base64 PSK."""
-        from utils.meshtastic import MeshtasticClient
         import base64
 
+        from utils.meshtastic import MeshtasticClient
+
         client = MeshtasticClient()
         # 32-byte key encoded as base64
         key = b'A' * 32
@@ -197,9 +198,10 @@ class TestPSKParsing:
 
     def test_parse_psk_simple_passphrase(self):
         """Should hash simple passphrase to 32-byte key."""
-        from utils.meshtastic import MeshtasticClient
         import hashlib
 
+        from utils.meshtastic import MeshtasticClient
+
         client = MeshtasticClient()
         result = client._parse_psk('simple:MySecretPassword')
 
@@ -218,9 +220,10 @@ class TestPSKParsing:
 
     def test_parse_psk_raw_base64(self):
         """Should accept raw base64 without prefix."""
-        from utils.meshtastic import MeshtasticClient
         import base64
 
+        from utils.meshtastic import MeshtasticClient
+
         client = MeshtasticClient()
         key = b'B' * 16
         encoded = base64.b64encode(key).decode()
@@ -261,6 +264,7 @@ class TestMeshtasticRoutes:
     def app(self):
         """Create Flask test app."""
         from flask import Flask
+
         from routes.meshtastic import meshtastic_bp
 
         app = Flask(__name__)