Fix #139: drop unsafe-inline from script-src and style-src (#139)

- Move all inline <script> blocks (layout head/theme, topbar dark toggle,
  foot, paste, new, history, mine, settings, admin, unlock) to external
  files under internal/web/static/. Page data reaches scripts via data-*
  attributes (data-paste-id, data-default-dark) instead of template vars.
- Replace inline onclick handlers (copy, delete, stats toggle) with
  addEventListener wiring.
- Convert inline style="" attributes to CSS utility classes; swatch
  colors are now set via CSSOM/DOM APIs instead of innerHTML strings.
- script-src/style-src are now plain 'self'; img-src data: stays for the
  SVG data-URI backgrounds. Verified with headless chromium: zero CSP
  violations on all pages in dark and light presets, theme swatches,
  admin lock, tables and paste view render correctly.

internal/web/static/history.js

@@ -0,0 +1,20 @@
+// #139: public history table + 30s auto-refresh.
+const t = PaletteTable.init({
+  endpoint: '/api/public',
+  perPage: 25,
+  hasPager: true,
+  rowHtml: it =>
+    `<tr class="row" data-href="/${t.esc(it.id)}"><td>` +
+    (it.title
+      ? `${t.esc(it.title)}${it.is_can ? ' <span class="badge" title="Can — bundle of items">can</span>' : ''}`
+      : `<a class="slug paste-name" href="/${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}">${t.ago(it.created_at)}</td>` +
+    (it.custom_slug ? `<td><a class="slug url-link" href="/${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.',
+});
+t.load();
+setInterval(t.load, 30000); // auto-refresh history every 30s