Fix #146: render untitled paste ID fallback as plain text like titled pastes

The PASTE column fallback for untitled pastes used the .slug class, which
renders as a monospace chip with a background pill. Give it a dedicated
paste-name modifier that strips the chip styling (background, padding,
radius, mono font) so the fallback looks identical to a titled paste
(var(--fg) plain text). The dedicated ID column and URL column chips keep
their existing styling. Applied to both /history and /mine tables.

internal/web/templates/history.html

@@ -37,7 +37,7 @@ const t = PaletteTable.init({
     `<tr class="row" data-href="/${t.esc(it.id)}"><td>` +
     (it.title
       ? `${t.esc(it.title)}${it.is_can ? ' <span class="badge" title="Can — bundle of items">can</span>' : ''}`
-      : `<a class="slug" href="/${t.esc(it.id)}">${t.esc(it.id)}</a>${it.is_can ? ' <span class="badge" title="Can — bundle of items">can</span>' : ''}`) +
+      : `<a class="slug paste-name" href="/${t.esc(it.id)}">${t.esc(it.id)}</a>${it.is_can ? ' <span class="badge" title="Can — bundle of items">can</span>' : ''}`) +
     `</td>` +
     `<td><span class="badge">${t.esc(it.language || 'text')}</span></td>` +
     `<td class="dim">${t.fmtSize(it.size)}</td><td class="dim">${it.view_count}</td><td class="dim" data-ts="${it.created_at}">${t.ago(it.created_at)}</td>` +