feat(about): show the desktop version and the web build's commit and date (#276)

Settings → About only showed cinny's package version, the same on web
and desktop and unchanged across many deploys a day. vite.config.js now
stamps the short commit (git, or LOTUS_BUILD_COMMIT; "unknown" without
git) and build time into the bundle, and About shows "Web build <commit>
· built <date>", linking the commit. On desktop it also shows "Desktop
<version>" from Tauri's built-in plugin:app|version (allowed by
core:default).

Fixes #276

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

vite.config.js

@@ -6,6 +6,7 @@ import { viteStaticCopy } from 'vite-plugin-static-copy';
 import { vanillaExtractPlugin } from '@vanilla-extract/vite-plugin';
 import { VitePWA } from 'vite-plugin-pwa';
 import fs from 'fs';
+import { execSync } from 'child_process';
 import path from 'path';
 import buildConfig from './build.config';
 
@@ -272,8 +273,26 @@ const vendorChunks = (id) => {
   if (id.includes('node_modules/chroma-js')) return 'chroma';
 };
 
+// [Gitea #276] Which build is this? The short commit and build time are shown
+// in Settings → About (web deploys change many times a day while the package
+// version stays the same). LOTUS_BUILD_COMMIT overrides; no git → "unknown".
+const buildCommit = (() => {
+  if (process.env.LOTUS_BUILD_COMMIT) return process.env.LOTUS_BUILD_COMMIT.slice(0, 12);
+  try {
+    return execSync('git rev-parse --short=8 HEAD', { stdio: ['ignore', 'pipe', 'ignore'] })
+      .toString()
+      .trim();
+  } catch {
+    return 'unknown';
+  }
+})();
+
 export default defineConfig({
   appType: 'spa',
+  define: {
+    __LOTUS_BUILD_COMMIT__: JSON.stringify(buildCommit),
+    __LOTUS_BUILD_DATE__: JSON.stringify(new Date().toISOString()),
+  },
   publicDir: false,
   base: buildConfig.base,
   server: {