feat(server): task 6.1/6.3 — dedicated server export preset and a real CLI surface

6.1: "Linux Dedicated Server" preset (dedicated_server=true,
custom_features="dedicated_server") mirroring the existing training
preset, plus run/main_scene.dedicated_server so the server binary reaches
its own entry point with no flag. Builds: an 85MB Linux x86_64 binary,
gitignored like the training one.

6.3: scripts/server_config.gd declares every server flag once - name,
type, default, section, help - and one parser turns that into parsing,
type checking, range validation, config-file backing and --help. The
flags had grown to ~30 across server_boot.gd and networked_match.gd, each
parsed inline with begins_with, none documented, and an unrecognised flag
was SILENTLY IGNORED: --max-clientss=8 ran a server on the default cap
and said nothing. Unknown flags, missing values, wrong types, duplicates
and out-of-range values are now hard errors, reported all at once.

Precedence is command line > config file > default. server_boot.gd parses
strictly because it owns the whole command line; networked_match.gd reads
the same declaration leniently because it is one consumer of an argv the
smoke harnesses also fill with --role= and --drive-seconds=. Nothing is
lost - every server flag is declared, so the strict pass already caught
any typo before the match scene re-reads its own.

13 unit tests covering the precedence order, the typo rejection that
motivated this, --no-<bool> not double-listing in --help, and --help
documenting every flag asserted against the declaration rather than a
hand-kept list. Verified end to end: --help prints, a typo'd flag refuses
to start, and the plain/replay-log/late-joiner smoke scenarios still pass.

Game/scripts/networked_match.gd

@@ -320,31 +320,31 @@ func _ready() -> void:
 	if kickoff_rng_seed == 0:
 		_kickoff_rng.randomize()
 	if multiplayer.is_server():
-		for arg: String in OS.get_cmdline_user_args():
-			if arg == "--fill-bots":
-				_fill_bots = true
-			elif arg == "--no-fill-bots":
-				_fill_bots = false
-			elif arg.begins_with("--max-spectators="):
-				_max_spectators = maxi(0, arg.get_slice("=", 1).to_int())
-			elif arg.begins_with("--replay-log="):
-				# Task 5.10. Diagnostic only: a log that cannot be opened must
-				# never stop the server serving the match.
-				var replay_path := arg.get_slice("=", 1)
-				_replay_log = ReplayLog.new()
-				var replay_err := _replay_log.open_for_write(replay_path)
-				if replay_err != OK:
-					push_warning("NetworkedMatch: could not open replay log %s (%s)" % [replay_path, error_string(replay_err)])
-					_replay_log = null
-				else:
-					print("NetworkedMatch: recording replay log to %s" % replay_path)
-			elif arg.begins_with("--slot-reservation-seconds="):
-				_slot_reservation_seconds = maxf(0.0, arg.get_slice("=", 1).to_float())
-			elif arg.begins_with("--match-length="):
-				# Regulation is 150s; a smoke test cannot wait that long to see
-				# FULL_TIME/OVERTIME/RESULTS, so allow an override. Server-side
-				# only — a client cannot shorten anyone's match.
-				match_length_seconds = maxf(1.0, arg.get_slice("=", 1).to_float())
+		# Task 6.3: the same declaration server_boot.gd validated, re-read here
+		# LENIENTLY — this scene is one consumer of an argv the smoke harnesses
+		# also fill with --role=, --drive-seconds= and client-side flags. The
+		# strict pass at the process entry point already rejected any typo in a
+		# server flag, so nothing is lost by ignoring what is not ours.
+		var config := ServerConfig.parse(OS.get_cmdline_user_args(), false)
+		_fill_bots = bool(config.get_value("fill-bots"))
+		var spectator_cap := int(config.get_value("max-spectators"))
+		_max_spectators = spectator_cap if spectator_cap < 0 else maxi(0, spectator_cap)
+		_slot_reservation_seconds = maxf(0.0, float(config.get_value("slot-reservation-seconds")))
+		# Regulation is 150s; a smoke test cannot wait that long to see
+		# FULL_TIME/OVERTIME/RESULTS, so allow an override. Server-side only —
+		# a client cannot shorten anyone's match.
+		match_length_seconds = maxf(1.0, float(config.get_value("match-length")))
+		var replay_path := String(config.get_value("replay-log"))
+		if not replay_path.is_empty():
+			# Task 5.10. Diagnostic only: a log that cannot be opened must
+			# never stop the server serving the match.
+			_replay_log = ReplayLog.new()
+			var replay_err := _replay_log.open_for_write(replay_path)
+			if replay_err != OK:
+				push_warning("NetworkedMatch: could not open replay log %s (%s)" % [replay_path, error_string(replay_err)])
+				_replay_log = null
+			else:
+				print("NetworkedMatch: recording replay log to %s" % replay_path)
 		_start_server()
 	else:
 		for arg: String in OS.get_cmdline_user_args():