#296 r2: restore URL column to position 6 and widen to 340px

Reverts PR #297's column reorder (owner override): URL returns to position
6 in both list tables (Paste, Type, Size, Views, Created, URL, ID; /mine
without Views), data-sort attrs and td cells move back together. Keeps
#297's non-position improvements: /mine URL uses the shared .col-url class
instead of reusing col-e, and mine's ID column returns to .col-f (100px).

Widens .col-url 150px -> 340px so a ~20-char slug displays fully at
1400x900; genuinely long custom slugs keep text ellipsis. No mobile media
query needed: <=640px already scrolls the table horizontally (min-width
720px), verified at 375x812.

Verified via CDP probe at 1400x900 and 375x812 on /history and /mine:
column order, colgroup/header alignment, sort arrow right of label, no
other column clipped, no CSP changes (no inline styles added).

internal/web/static/history.js

@@ -9,9 +9,9 @@ const t = PaletteTable.init({
       ? `<a class="paste-name" href="/${t.esc(it.id)}">${t.esc(it.title)}</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>` +
-    (it.custom_slug ? `<td><a class="slug url-link" href="/${t.esc(it.custom_slug)}">/${t.esc(it.custom_slug)}</a></td>` : `<td class="dim">none</td>`) +
     `<td><span class="badge">${t.esc(it.type || it.language || 'text')}</span></td>` +
     `<td class="dim">${t.fmtSize(it.size)}</td><td class="dim">${it.view_count}</td><td class="dim" data-ts="${it.created_at}">${t.ago(it.created_at)}</td>` +
+    (it.custom_slug ? `<td><a class="slug url-link" href="/${t.esc(it.custom_slug)}">/${t.esc(it.custom_slug)}</a></td>` : `<td class="dim">none</td>`) +
     `<td class="dim"><a class="id-link" href="/${t.esc(it.id)}">${t.esc(it.id)}</a></td></tr>`,
   emptyFiltered: 'No pastes match your search.',
   emptyAll: 'No pastes yet. Create the first one.',