Add domain CRUD, energy density constraint, LLM status, reset results, score display fixes

Domain management:
- Add domain list/detail/form templates and full CRUD routes (domains.py)
- Add metric bound add/edit/delete via HTMX partials (_metrics_table.html)

Energy density constraint (Rule 6 in ConstraintResolver):
- Hard-block combos where power source provides <25% of platform's required Wh/kg
- Warn (conditional) when under-density but within 4x
- Solar Sail exempt (no stored energy); Airplane requires 400 Wh/kg, Spaceship 2000 Wh/kg
- Add energy_density_wh_kg provides to all 8 stored-energy power sources in seed data
- 3 new constraint resolver tests

LLM-complete status:
- Pipeline Pass 4 now sets combo status to llm_reviewed after successful LLM review
- update_combination_status guards against downgrading: scored won't overwrite
  llm_reviewed or reviewed; llm_reviewed won't overwrite reviewed
- Add badge-llm_reviewed CSS style (light blue)

Reset results:
- Repository.reset_domain_results() deletes combination_results, combination_scores,
  and pipeline_runs for a domain; pipeline re-evaluates on next run
- POST /results/<domain>/reset route with flash confirmation
- "Reset results" danger button with JS confirm dialog in results list

Fix composite score 0 displaying as --- (Jinja2 falsy 0.0 bug):
- Change `if r.composite_score` to `if r.composite_score is not none`

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

src/physcom_web/templates/results/list.html

@@ -15,7 +15,14 @@
 
 {% if domain and results is not none %}
 <div class="card">
-  <h2>{{ domain.name }} <span class="subtitle">{{ domain.description }}</span></h2>
+  <div class="page-header">
+    <h2>{{ domain.name }} <span class="subtitle">{{ domain.description }}</span></h2>
+    <form method="post" action="{{ url_for('results.reset_results', domain_name=domain.name) }}"
+          class="inline-form"
+          onsubmit="return confirm('Delete all results for {{ domain.name }}? This cannot be undone.')">
+      <button type="submit" class="btn btn-danger btn-sm">Reset results</button>
+    </form>
+  </div>
 
   {% if statuses %}
   <div class="filter-row">
@@ -53,7 +60,7 @@
       {% for r in results %}
       <tr>
         <td>{{ loop.index }}</td>
-        <td class="score-cell">{{ "%.4f"|format(r.composite_score) if r.composite_score else '—' }}</td>
+        <td class="score-cell">{{ "%.4f"|format(r.composite_score) if r.composite_score is not none else '—' }}</td>
         <td>{{ r.combination.entities|map(attribute='name')|join(' + ') }}</td>
         <td><span class="badge badge-{{ r.combination.status }}">{{ r.combination.status }}</span></td>
         <td class="block-reason-cell">