fix(content): argparse --dry-run for generate_corp_stubs.py; populate cross_refs (#828 nits)

- generate_corp_stubs.py: add argparse with --dry-run (prints planned stub
  creations without writing files) and --help
- calloway-distillery.md: cross_refs → [thrds, mercado-travessia]
- thrds.md: cross_refs → [calloway-distillery, mercado-travessia]
- vins-de-grand-vide.md: cross_refs → [nordmark-skog]
- thalassa-resort-group.md: cross_refs → [the-registry, prometheus-labs]

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

wiki/corporations/calloway-distillery.md

@@ -11,7 +11,7 @@ faction_type: economic
 headquarters: Calloway Reach (GJ 3325)
 tags: []
 decision_refs: []
-cross_refs: []
+cross_refs: [thrds, mercado-travessia]
 ---
 
 # Calloway Distillery

wiki/corporations/thalassa-resort-group.md

@@ -11,7 +11,7 @@ faction_type: economic
 headquarters: Gateway (GJ 244A)
 tags: [hospitality, fine_dining, entertainment, tractus, assembly, gateway]
 decision_refs: [D-175]
-cross_refs: []
+cross_refs: [the-registry, prometheus-labs]
 ---
 
 # Thalassa Resort Group

wiki/corporations/thrds.md

@@ -11,7 +11,7 @@ faction_type: economic
 headquarters: Braemar (GJ 475)
 tags: []
 decision_refs: []
-cross_refs: []
+cross_refs: [calloway-distillery, mercado-travessia]
 ---
 
 # thrds

wiki/corporations/vins-de-grand-vide.md

@@ -11,7 +11,7 @@ faction_type: economic
 headquarters: Confluent (GJ 395)
 tags: []
 decision_refs: []
-cross_refs: []
+cross_refs: [nordmark-skog]
 ---
 
 # Vins de Grand Vide