fix(simulation): resolve corp_presence location granularity bug (#805)

import_corp_presence() was inserting system IDs with location_type='system',
violating the schema which expects body/station IDs (location_type='body'|'station').

Fix:
- import_economics.py: add _resolve_hq_location() that picks the most-populated
  body in the HQ system (falling back to any body, then any station)
- econ-sim/db.rs: load_corp_presences() now JOINs bodies/stations to recover
  system_id from body/station location_ids, dropping the 'system' filter

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

tooling/econ-sim/src/db.rs

@@ -282,12 +282,18 @@ fn load_gate_links(conn: &Connection) -> Vec<GateLink> {
 }
 
 fn load_corp_presences(conn: &Connection) -> Vec<CorpPresence> {
+    // Resolve body/station location_id back to system_id via LEFT JOINs.
+    // corp_presence.location_type is 'body' | 'station' per schema.
     let mut stmt = conn
         .prepare(
-            "SELECT corp_id, location_id, primary_operation
-             FROM corp_presence
-             WHERE location_type = 'system'
-             ORDER BY location_id, corp_id",
+            "SELECT cp.corp_id,
+                    COALESCE(b.system_id, s.system_id) AS system_id,
+                    cp.primary_operation
+             FROM corp_presence cp
+             LEFT JOIN bodies b ON cp.location_type = 'body' AND cp.location_id = b.body_id
+             LEFT JOIN stations s ON cp.location_type = 'station' AND cp.location_id = s.station_id
+             WHERE COALESCE(b.system_id, s.system_id) IS NOT NULL
+             ORDER BY system_id, cp.corp_id",
         )
         .expect("prepare corp_presence");