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>

utils/updater.py

@@ -4,6 +4,7 @@ GitHub update checking and git-based update mechanism.
 
 from __future__ import annotations
 
+import contextlib
 import json
 import logging
 import os
@@ -264,10 +265,8 @@ def get_update_status() -> dict[str, Any]:
 
     last_check_time = None
     if last_check:
-        try:
+        with contextlib.suppress(ValueError, TypeError):
             last_check_time = datetime.fromtimestamp(float(last_check)).isoformat()
-        except (ValueError, TypeError):
-            pass
 
     return {
         'success': True,