Fix log viewer readability — add missing CSS utility classes (#244)

* fix(web): add missing utility classes for log viewer readability

The log viewer uses text-gray-100, text-gray-200, text-gray-300,
text-red-300, text-yellow-300, bg-gray-800, bg-red-900, bg-yellow-900,
border-gray-700, and hover:bg-gray-800 — none of which were defined in
app.css. Without definitions, log text inherited the body's dark color
(#111827) which was invisible against the dark bg-gray-900 log container
in light mode.

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

* fix(web): remove dead bg-opacity classes, use proper log level colors

The bg-opacity-10/bg-opacity-30 classes set a --bg-opacity CSS variable
that no background-color rule consumed, making them dead code. Replace
the broken two-class pattern (e.g. "bg-red-900 bg-opacity-10") with
dedicated log-level-error/warning/debug classes that use rgb() with
actual alpha values.

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

---------

Co-authored-by: Chuck <chuck@example.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

web_interface/templates/v3/partials/logs.html

@@ -380,10 +380,10 @@ function renderLogs() {
 function getLogLevelClass(level) {
     // Background color for the entire log entry row
     const classes = {
-        'ERROR': 'bg-red-900 bg-opacity-10',
-        'WARNING': 'bg-yellow-900 bg-opacity-10',
+        'ERROR': 'log-level-error',
+        'WARNING': 'log-level-warning',
         'INFO': '',
-        'DEBUG': 'bg-gray-800 bg-opacity-30'
+        'DEBUG': 'log-level-debug'
     };
     return classes[level] || '';
 }