refactor(layout-review): consolidate tool-header actions + align reconcile downloads

Consistency pass over the parallel-agent work:
- Replace 4 divergent inline header wrappers (flex/inline-flex, gap
  10/12px, margin-top present/absent across 8 tool pages) with one shared
  .dt-tool-header-actions class; strip the now-redundant per-button
  margin-top:0. Every tool header now aligns the local-first pill + Help
  button identically.
- Reconcile downloads row: reorder to the page's exceptions-first order
  (Review, Unmatched left, Unmatched right, Matched) to match the tabs and
  metric strip, and drop the lone competing primary — the four are
  parallel exports of equal weight.

Audited and confirmed already-consistent: compact intake banner, privacy
pill markup, .dt-next-step strips, the three coming-soon stubs, primary
CTAs, and the 3-download CSV/audit/config pattern.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

layout-review/05_column_mapper.html

@@ -19,7 +19,7 @@
       <!-- Tool header -->
       <div class="dt-tool-header">
         <h1>Map Columns</h1>
-        <div style="display:flex;align-items:center;gap:12px">
+        <div class="dt-tool-header-actions">
           <span class="dt-privacy-pill">
             <svg viewBox="0 0 24 24" fill="none" stroke="currentColor">
               <rect x="4" y="11" width="16" height="10" rx="2"/>