fix(plugins): show last-modified date on plugin cards, not first-published (#368)

* ui(installer): centre the one-liner box and add vertical breathing room

The `.max-w-xl` quick-install container sat flush-left against the
hero copy with only `mt-4` above it, so on wider viewports it
hugged the left gutter and crowded the subhead. Add `mx-auto` to
centre it within the `.wrap`, `my-8` to give it clear vertical
separation from the paragraph above and the demo gif below, and
`p-2` to pad the tab/command/caption stack away from the border.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(plugins): show last-modified date on plugin cards instead of first-published

The date next to each plugin's version was rendered from
\`plugins.time\` — the npm first-publish timestamp, which stays fixed
for the lifetime of the package. That's why actively-maintained
plugins like ep_list_pads (first published 2025-08-25, last modified
2026-04-15) were reading as "8 months ago" on /plugins even though
a new version shipped two days earlier.

Render \`plugins.modified\` (npm last-publish timestamp) instead, so
the card reflects actual recency. Exact ISO date is kept as a tooltip
for anyone who wants it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: JohnMcLear

src/components/Plugin.tsx

@@ -55,7 +55,7 @@ export const PluginCom: FC<PluginProps> = ({plugins}) => {
                 <small className="align-text-bottom text-gray-400 mt-[3px]">{plugins.version}</small>
             </div>
             <div className="grow"></div>
-            {plugins.time && <div className="mr-5 mt-[0.3rem]">{formatTime(plugins.time)}</div>}
+            {plugins.modified && <div className="mr-5 mt-[0.3rem]" title={`Last updated ${plugins.modified}`}>{formatTime(plugins.modified)}</div>}
             <div className="w-10 flex items-center mr-2">
                 <div className="w-10 border-[1px] border-white"
                      title={(plugins.downloads) + " downloads"}>