fix(ui): address PR #124 review — navigation, error handling, cleanup

- Economics panel: replace dead _gui_input LEFT/RIGHT with public
  navigate() method, wire [ ] keys in main.gd (avoids movement
  key conflict, fixes focus_mode=NONE issue)
- Debug console: add explicit effect guard in econ inject no-commodity
  branch so invalid effects don't fall to commodity-form error
- Snapshot consumer: null-clear GameState.economy_snapshot after
  consuming (matches one-shot consumer invariant)
- Star map: remove duplicate doc comment above set_insert_active()
- Generate script: remove stale comment, dead _WORKTREE_PARENT var,
  dead field extraction in parse_wiki_index, add try/except around
  DB queries

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

client/scripts/main.gd

@@ -176,6 +176,14 @@ func _unhandled_key_input(event: InputEvent) -> void:
 			# #824: E — toggle Economics Monitor implant panel
 			if economics_panel:
 				economics_panel.toggle_visible()
+		elif event is InputEventKey and event.keycode == KEY_BRACKETLEFT:
+			# #824: [ — cycle economics panel system selector backward
+			if economics_panel and HudGroups.is_app_active("implant/economics"):
+				economics_panel.navigate(-1)
+		elif event is InputEventKey and event.keycode == KEY_BRACKETRIGHT:
+			# #824: ] — cycle economics panel system selector forward
+			if economics_panel and HudGroups.is_app_active("implant/economics"):
+				economics_panel.navigate(1)
 
 
 func _process(delta: float) -> void:

client/scripts/snapshot_consumers.gd

@@ -183,6 +183,7 @@ func consume_economy_snapshot() -> void:
 		return
 	if economics_panel.has_method("receive_economy_data"):
 		economics_panel.receive_economy_data(GameState.economy_snapshot)
+	GameState.economy_snapshot = null
 
 
 # #174: Consume examine result — show overlay when server sends character-filtered observation.