fix(sql): add ORDER BY to all LIMIT queries for deterministic results

SQLite does not guarantee row order without ORDER BY, even with LIMIT.
This was a systemic issue found during a multi-pass bug hunt:

Production queries (explain.rs):
- Outgoing reference query: ORDER BY target_entity_type, target_entity_iid
- Incoming reference query: ORDER BY source_entity_type, COALESCE(iid)
  Without these, robot mode output was non-deterministic across calls,
  breaking clients expecting stable ordering.

Test helper queries (5 locations across 3 files):
- discussions_tests.rs: get_discussion_id()
- mr_discussions.rs: get_mr_discussion_id()
- queue.rs: setup_db_with_job(), release_all_locked_jobs_clears_locks()
  Currently safe (single-row inserts) but would break silently if tests
  expanded to multi-row fixtures.

src/cli/commands/explain.rs

@@ -821,7 +821,8 @@ fn fetch_related_entities(
          LEFT JOIN merge_requests mr ON er.target_entity_type = 'merge_request' AND mr.id = er.target_entity_id \
          WHERE er.source_entity_type = ?1 AND er.source_entity_id = ?2 \
            AND er.reference_type != 'closes' \
-           AND er.target_entity_iid IS NOT NULL",
+           AND er.target_entity_iid IS NOT NULL \
+         ORDER BY er.target_entity_type, er.target_entity_iid",
     )?;
 
     let outgoing: Vec<RelatedEntityInfo> = out_stmt
@@ -845,7 +846,8 @@ fn fetch_related_entities(
          LEFT JOIN merge_requests mr ON er.source_entity_type = 'merge_request' AND mr.id = er.source_entity_id \
          WHERE er.target_entity_type = ?1 AND er.target_entity_id = ?2 \
            AND er.reference_type != 'closes' \
-           AND COALESCE(i.iid, mr.iid) IS NOT NULL",
+           AND COALESCE(i.iid, mr.iid) IS NOT NULL \
+         ORDER BY er.source_entity_type, COALESCE(i.iid, mr.iid)",
     )?;
 
     let incoming: Vec<RelatedEntityInfo> = in_stmt
@@ -1020,7 +1022,7 @@ pub fn handle_explain(
     let elapsed_ms = start.elapsed().as_millis() as u64;
 
     if robot_mode {
-        print_explain_json(&result, elapsed_ms);
+        print_explain_json(&result, elapsed_ms)?;
     } else {
         print_explain(&result);
     }
@@ -1032,13 +1034,18 @@ pub fn handle_explain(
 // Output rendering (Task 5 fills these in fully)
 // ---------------------------------------------------------------------------
 
-pub fn print_explain_json(result: &ExplainResult, elapsed_ms: u64) {
+pub fn print_explain_json(result: &ExplainResult, elapsed_ms: u64) -> Result<()> {
     let response = serde_json::json!({
         "ok": true,
         "data": result,
         "meta": { "elapsed_ms": elapsed_ms }
     });
-    println!("{}", serde_json::to_string(&response).unwrap_or_default());
+    println!(
+        "{}",
+        serde_json::to_string(&response)
+            .map_err(|e| LoreError::Other(format!("JSON serialization failed: {e}")))?
+    );
+    Ok(())
 }
 
 pub fn print_explain(result: &ExplainResult) {