Display metric units in web UI, make seed idempotent, simplify code

- Load m.unit in get_domain() so MetricBound carries units from DB
- Add Unit column to domains list template
- Make load_transport_seed() idempotent with IntegrityError handling
  and metric unit backfill for existing DBs
- Remove unused imports (json, sqlite3, Entity)
- Simplify combinator loop to list comprehension
- Merge duplicate conditional/valid branches in pipeline
- Consolidate duplicated SQL in get_all_results()
- Expand CLAUDE.md with fuller architecture docs and conventions

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

src/physcom/db/repository.py

@@ -204,7 +204,7 @@ class Repository:
         if not row:
             return None
         weights = self.conn.execute(
-            """SELECT m.name, dmw.weight, dmw.norm_min, dmw.norm_max, dmw.metric_id
+            """SELECT m.name, m.unit, dmw.weight, dmw.norm_min, dmw.norm_max, dmw.metric_id
                FROM domain_metric_weights dmw
                JOIN metrics m ON dmw.metric_id = m.id
                WHERE dmw.domain_id = ?""",
@@ -218,7 +218,7 @@ class Repository:
                 MetricBound(
                     metric_name=w["name"], weight=w["weight"],
                     norm_min=w["norm_min"], norm_max=w["norm_max"],
-                    metric_id=w["metric_id"],
+                    metric_id=w["metric_id"], unit=w["unit"] or "",
                 )
                 for w in weights
             ],
@@ -411,26 +411,17 @@ class Repository:
 
     def get_all_results(self, domain_name: str, status: str | None = None) -> list[dict]:
         """Return all results for a domain, optionally filtered by combo status."""
+        query = """SELECT cr.*, c.hash, c.status as combo_status, d.name as domain_name
+                   FROM combination_results cr
+                   JOIN combinations c ON cr.combination_id = c.id
+                   JOIN domains d ON cr.domain_id = d.id
+                   WHERE d.name = ?"""
+        params: list = [domain_name]
         if status:
-            rows = self.conn.execute(
-                """SELECT cr.*, c.hash, c.status as combo_status, d.name as domain_name
-                   FROM combination_results cr
-                   JOIN combinations c ON cr.combination_id = c.id
-                   JOIN domains d ON cr.domain_id = d.id
-                   WHERE d.name = ? AND c.status = ?
-                   ORDER BY cr.composite_score DESC""",
-                (domain_name, status),
-            ).fetchall()
-        else:
-            rows = self.conn.execute(
-                """SELECT cr.*, c.hash, c.status as combo_status, d.name as domain_name
-                   FROM combination_results cr
-                   JOIN combinations c ON cr.combination_id = c.id
-                   JOIN domains d ON cr.domain_id = d.id
-                   WHERE d.name = ?
-                   ORDER BY cr.composite_score DESC""",
-                (domain_name,),
-            ).fetchall()
+            query += " AND c.status = ?"
+            params.append(status)
+        query += " ORDER BY cr.composite_score DESC"
+        rows = self.conn.execute(query, params).fetchall()
         results = []
         for r in rows:
             combo = self.get_combination(r["combination_id"])