Add async pipeline with progress monitoring, resumability, and result transparency

Pipeline engine rewritten with combo-first loop: each combination is processed
through all requested passes before moving to the next, with incremental DB
saves after every step (crash-safe). Blocked combos now get result rows so they
appear in the results page with constraint violation reasons.

New pipeline_runs table tracks run lifecycle (pending/running/completed/failed/
cancelled). Web route launches pipeline in a background thread with its own DB
connection. HTMX polling partial shows live progress with per-pass breakdown.

Also: status guard prevents reviewed->scored downgrade, save_combination loads
existing status on dedup for correct resume, per-metric scores show domain
bounds + units + position bars, ensure_metric backfills units on existing rows.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/physcom_web/templates/domains/list.html

@@ -7,14 +7,13 @@
 {% if not domains %}
 <p class="empty">No domains found. Seed data via CLI first.</p>
 {% else %}
-<div class="card-grid">
   {% for d in domains %}
   <div class="card">
     <h2>{{ d.name }}</h2>
     <p>{{ d.description }}</p>
     <table>
       <thead>
-        <tr><th>Metric</th><th>Weight</th><th>Min</th><th>Max</th></tr>
+        <tr><th>Metric</th><th>Weight</th><th>Norm Min</th><th>Norm Max</th></tr>
       </thead>
       <tbody>
         {% for mb in d.metric_bounds %}
@@ -29,6 +28,5 @@
     </table>
   </div>
   {% endfor %}
-</div>
 {% endif %}
 {% endblock %}