fix(economics): restore dropped vocab_rows.append in import_system_specialization

The #1015 V-SES-03 edit replaced the vocabulary validation loop body and
dropped the trailing vocab_rows.append(), so specialization_vocabulary was
inserted with 0 rows even though per-system UPSERTs (which read the dict
directly via valid_spec_ids) still succeeded. regen-db reported
'vocab 0 | economic 27 | ...'. Restored the append at the end of the loop.

Verified: regen-db now writes 27 vocab rows + 27/27 economic/cultural;
spot checks financial_hub=NonPhysical/Specialist, Ran=breadbasket.

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

tooling/economy-db/import_economics.py

@@ -1730,6 +1730,7 @@ def import_system_specialization(conn: sqlite3.Connection, dry_run: bool,
                     f"'{override}' is less concentrated than commodity "
                     f"'{cid}' catalog default '{commodity_pu[cid]}' — incoherent"
                 )
+        vocab_rows.append((spec_id, cid, override, bc, pu, v.get("description", "")))
 
     valid_spec_ids = set(vocab.keys())