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/conftest.py

@@ -1,9 +1,11 @@
 """Pytest configuration and fixtures."""
 
+import contextlib
 import sqlite3
 from unittest.mock import MagicMock, patch
 
 import pytest
+
 from app import app as flask_app
 from routes import register_blueprints
 
@@ -80,9 +82,10 @@ def mock_app_state():
 
     Provides mock process, queue, and lock objects on the app module.
     """
-    import app as app_module
     import queue
 
+    import app as app_module
+
     mock_process = MagicMock()
     mock_process.poll.return_value = None
     mock_queue = queue.Queue()
@@ -107,10 +110,8 @@ def mock_app_state():
 
     for attr, orig in originals.items():
         if orig is None:
-            try:
+            with contextlib.suppress(AttributeError):
                 delattr(app_module, attr)
-            except AttributeError:
-                pass
         else:
             setattr(app_module, attr, orig)