fix: use primary foreground color with opacity for auto badge

--text-secondary (vscode-descriptionForeground) is too dark in some
dark themes. Switch to --text-primary (vscode-editor-foreground) at
55% opacity for both the border and text. VS Code guarantees the
primary foreground color is always readable against the editor
background, so this reliably produces visible but visually subtle
badge text in any theme.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: rajbos

vscode-extension/src/webview/usage/styles.css

@@ -362,8 +362,9 @@ background: var(--bg-tertiary);
 	padding: 1px 5px;
 	font-size: 10px;
 	border-radius: 3px;
-	border: 1px solid var(--text-secondary);
-	color: var(--text-secondary);
+	border: 1px solid var(--text-primary);
+	color: var(--text-primary);
+	opacity: 0.55;
 	background: transparent;
 	vertical-align: middle;
 	line-height: 1.4;