fix(theme): button text uses VS Code theme tokens for contrast (1.5.2)

Action buttons (Apply Changes, Add Row, Create Table, Export, Save, …)
drew their label in hardcoded `color: white`, which could fall below a
readable contrast on custom VS Code themes whose button/accent colors
are light (#436).

`.btn-primary` now uses `--vscode-button-background`/`-foreground` with
`--vscode-button-hoverBackground` on hover; `.btn-secondary` uses the
`--vscode-button-secondary*` tokens; `.btn-danger` keeps its
error-colored background with `--vscode-button-foreground` text; and
`.cell-preview-toolbar-btn.active` uses `--vscode-button-foreground`.
Each token carries a fallback matching the previous appearance so the
standalone web demo (rendered outside VS Code) is unchanged.

Bumps the extension to 1.5.2 (changelog updated). Build regenerates the
webview + web-demo bundles; 414/414 unit tests pass.

Closes #436

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: zknpr

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 1.5.2
+
+### Fixes
+
+- **Button text now follows the active VS Code theme instead of a hardcoded white.** Action buttons (Apply Changes, Add Row, Create Table, Export, Save, …) drew their label in hardcoded white, which could fall below a readable contrast on custom themes whose button/accent colors are light. The primary, secondary, and danger buttons — and the active cell-preview toolbar toggle — now use the built-in VS Code button theme tokens (`--vscode-button-background` / `-foreground` / `-hoverBackground` and the `secondary*` variants), so text/background contrast is defined by the active theme. Fallback values matching the previous appearance are retained for the standalone web demo, which renders outside VS Code. Closes #436.
+
 ## 1.5.1
 
 ### Fixes

core/ui/viewer.css

@@ -887,37 +887,46 @@ body {
 }
 
 .btn-primary {
-    background: var(--accent-color);
+    /* VS Code button theme tokens: text/background contrast is defined by the
+       active theme rather than hardcoded, so "Apply Changes" etc. stay legible
+       on custom themes. Fallbacks mirror the Dark+ defaults and keep the
+       standalone web demo (no --vscode-* vars) rendering unchanged. */
+    background: var(--vscode-button-background, #0e639c);
     border: none;
-    color: white;
+    color: var(--vscode-button-foreground, #ffffff);
     padding: 6px 14px;
     border-radius: 3px;
     cursor: pointer;
     font-size: 13px;
 }
 
 .btn-primary:hover {
-    opacity: 0.9;
+    /* Themed hover background replaces the previous opacity dim, which faded
+       the button-foreground text and hurt contrast on some themes. */
+    background: var(--vscode-button-hoverBackground, #1177bb);
 }
 
 .btn-secondary {
-    background: var(--bg-tertiary);
+    background: var(--vscode-button-secondaryBackground, #3c3c3c);
     border: 1px solid var(--border-color);
-    color: var(--text-primary);
+    color: var(--vscode-button-secondaryForeground, #cccccc);
     padding: 6px 14px;
     border-radius: 3px;
     cursor: pointer;
     font-size: 13px;
 }
 
 .btn-secondary:hover {
-    background: var(--hover-bg);
+    background: var(--vscode-button-secondaryHoverBackground, #2a2d2e);
 }
 
 .btn-danger {
+    /* No dedicated danger-button token exists; keep the error-colored
+       background and use button-foreground (white in the standard themes) for
+       readable text instead of a hardcoded white. */
     background: var(--error-color);
     border: none;
-    color: white;
+    color: var(--vscode-button-foreground, #ffffff);
     padding: 6px 14px;
     border-radius: 3px;
     cursor: pointer;
@@ -1073,7 +1082,7 @@ body {
 .cell-preview-toolbar-btn.active {
     background: var(--accent-color);
     border-color: var(--accent-color);
-    color: white;
+    color: var(--vscode-button-foreground, #ffffff);
 }
 
 .cell-preview-footer {