fix(simulation): address PR #122 review — determinism, correctness, labeling

- HashMap → BTreeMap throughout econ-sim for deterministic iteration (D-010)
- Fix cost_factor: multiplicative gate×zone instead of additive (trade.rs)
- Extract derive_seed to shared prng.rs, consolidate FNV-1a implementation
- Rename run_shock_test → run_no_explosion_check (not D-179 Test 3)
- Deduplicate cross-zone FX rate collection in Test 4
- Replace ORDER BY RANDOM() with deterministic ordering + ChaCha8Rng
- Make commodity coverage failure a hard error consistent with D-175
- Fix gap-fill off-by-one (4 corps → 3 when coverage = 0)
- Correct test report: EconEvent exists, location_type is body/station

All four D-179 stability tests still pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tooling/econ-sim/src/db.rs

@@ -1,6 +1,6 @@
 //! Database loading — reads economy data from systems.db.
 
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 use std::path::PathBuf;
 use std::process;
 
@@ -80,15 +80,15 @@ pub struct GateLink {
 /// The complete economics dataset loaded from systems.db.
 pub struct Economy {
     pub commodities: Vec<Commodity>,
-    pub commodity_map: HashMap<String, Commodity>,
+    pub commodity_map: BTreeMap<String, Commodity>,
     pub chains: Vec<ProductionChain>,
     /// Map: output_commodity_id → list of chains that produce it
-    pub chains_by_output: HashMap<String, Vec<ProductionChain>>,
+    pub chains_by_output: BTreeMap<String, Vec<ProductionChain>>,
     /// Map: system_id → SystemInfo
-    pub systems: HashMap<String, SystemInfo>,
+    pub systems: BTreeMap<String, SystemInfo>,
     pub corp_presences: Vec<CorpPresence>,
     /// Map: system_id → list of corp presences
-    pub presences_by_system: HashMap<String, Vec<CorpPresence>>,
+    pub presences_by_system: BTreeMap<String, Vec<CorpPresence>>,
     /// Bidirectional gate links (transport graph)
     pub gate_links: Vec<GateLink>,
     /// Raw corp data for archetype inference: (corp_id, behavioral_archetype?, specialization?)
@@ -193,12 +193,12 @@ fn load_chains(conn: &Connection) -> Vec<ProductionChain> {
         .collect();
 
     // Build index of chain_id → inputs
-    let mut input_map: HashMap<String, Vec<ChainInput>> = HashMap::new();
+    let mut input_map: BTreeMap<String, Vec<ChainInput>> = BTreeMap::new();
     for (chain_id, commodity_id, quantity) in all_inputs {
-        input_map
-            .entry(chain_id)
-            .or_default()
-            .push(ChainInput { commodity_id, quantity });
+        input_map.entry(chain_id).or_default().push(ChainInput {
+            commodity_id,
+            quantity,
+        });
     }
 
     for chain in &mut chains {
@@ -210,7 +210,7 @@ fn load_chains(conn: &Connection) -> Vec<ProductionChain> {
     chains
 }
 
-fn load_systems(conn: &Connection) -> HashMap<String, SystemInfo> {
+fn load_systems(conn: &Connection) -> BTreeMap<String, SystemInfo> {
     let mut stmt = conn
         .prepare(
             "SELECT ss.system_id, ss.proper_name, ss.cultural_corridor,
@@ -234,7 +234,9 @@ fn load_systems(conn: &Connection) -> HashMap<String, SystemInfo> {
             cultural_corridor: row.get(2)?,
             gate_energy_connected: row.get::<_, Option<i32>>(3)?.unwrap_or(1) != 0,
             population: row.get(4)?,
-            currency_zone: row.get::<_, Option<String>>(5)?.unwrap_or_else(|| "TRACTUS_PRIMARY".to_string()),
+            currency_zone: row
+                .get::<_, Option<String>>(5)?
+                .unwrap_or_else(|| "TRACTUS_PRIMARY".to_string()),
             hop_distance: row.get::<_, Option<i64>>(6)?.unwrap_or(5),
             gate_topology: row.get(7)?,
             political_zone: row.get(8)?,
@@ -246,9 +248,7 @@ fn load_systems(conn: &Connection) -> HashMap<String, SystemInfo> {
     .collect()
 }
 
-fn load_corp_archetype_data(
-    conn: &Connection,
-) -> Vec<(String, Option<String>, Option<String>)> {
+fn load_corp_archetype_data(conn: &Connection) -> Vec<(String, Option<String>, Option<String>)> {
     let mut stmt = conn
         .prepare(
             "SELECT corp_id, behavioral_archetype, specialization
@@ -315,11 +315,13 @@ fn load_corp_presences(conn: &Connection) -> Vec<CorpPresence> {
 
 pub fn load_economy(conn: &Connection) -> Economy {
     let commodities = load_commodities(conn);
-    let commodity_map: HashMap<String, Commodity> =
-        commodities.iter().map(|c| (c.id.clone(), c.clone())).collect();
+    let commodity_map: BTreeMap<String, Commodity> = commodities
+        .iter()
+        .map(|c| (c.id.clone(), c.clone()))
+        .collect();
 
     let chains = load_chains(conn);
-    let mut chains_by_output: HashMap<String, Vec<ProductionChain>> = HashMap::new();
+    let mut chains_by_output: BTreeMap<String, Vec<ProductionChain>> = BTreeMap::new();
     for chain in &chains {
         chains_by_output
             .entry(chain.output_commodity_id.clone())
@@ -330,7 +332,7 @@ pub fn load_economy(conn: &Connection) -> Economy {
     let systems = load_systems(conn);
     let corp_presences = load_corp_presences(conn);
 
-    let mut presences_by_system: HashMap<String, Vec<CorpPresence>> = HashMap::new();
+    let mut presences_by_system: BTreeMap<String, Vec<CorpPresence>> = BTreeMap::new();
     for cp in &corp_presences {
         presences_by_system
             .entry(cp.system_id.clone())