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/ui/debug_console.gd

@@ -287,6 +287,12 @@ func _econ_inject(parts: Array) -> void:
 		magnitude_str = args[2]
 		if args.size() >= 4:
 			ticks_str = args[3]
+	elif args.size() == 3:
+		# 3 args but args[1] isn't shock/boost — bad effect keyword, not a commodity
+		_append_text(
+			"econ inject: effect must be 'shock' or 'boost', got '%s'" % args[1], ERROR_COLOR
+		)
+		return
 	else:
 		# With commodity_id: econ inject <system> <commodity> <effect> <magnitude> [ticks]
 		commodity_id = args[1]