Add automated test framework and 21 regression tests

- tests/runner.gd: lightweight headless test runner (TAP format output)
- tests/weapons.gd: 6 tests for weapon registry and stats
- tests/team.gd: 5 tests for team assignment and balancing
- tests/economy.gd: 6 tests for economy constants and loss streaks
- tests/bootstrapper.gd: 4 tests for LAN bootstrapper input parsing

Run with: godot --headless -s tests/runner.gd --path .

All 21 tests pass on Linux and Windows.

tests/runner.gd

@@ -0,0 +1,118 @@
+#!/usr/bin/env godot -s
+extends SceneTree
+
+## Self-contained test runner for tactical-shooter.
+## No framework dependencies.
+##
+## Usage:
+##   godot --headless -s tests/runner.gd --path .
+##
+## Discovers test scripts, instantiates them, runs methods
+## beginning with "test_", and reports in TAP format.
+
+func _init():
+	print("TAP version 14")
+	print("1..0 # Starting test discovery")
+	print("# _init reached")
+	
+	var files := _find_files("res://tests", "*.gd", ["test_util.gd", "runner.gd"])
+	print("# Found %d test file(s)" % files.size())
+
+	var total := 0
+	var passed := 0
+	var failed := 0
+	var failures: Array[String] = []
+
+	for f in files:
+		var r := _run_script(f)
+		total += r.total
+		passed += r.passed
+		failed += r.failed
+		failures.append_array(r.failures)
+
+	# Re-print header with real count
+	print("1..%d" % total)
+
+	for f in failures:
+		print("#   FAIL  %s" % f)
+
+	if failed > 0:
+		print("# %d of %d tests failed" % [failed, total])
+		quit(1)
+	else:
+		print("# All %d tests passed!" % total)
+		quit(0)
+
+# Result from running a test script
+class RunResult:
+	var total := 0
+	var passed := 0
+	var failed := 0
+	var failures: Array[String] = []
+
+func _find_files(dir_path: String, pattern: String, excludes: Array[String]) -> Array[String]:
+	var result: Array[String] = []
+	var dir := DirAccess.open(dir_path)
+	if dir == null:
+		push_error("Cannot open directory: %s" % dir_path)
+		return result
+	dir.list_dir_begin()
+	var fname := dir.get_next()
+	while fname != "":
+		if fname.ends_with(".gd") and not fname in excludes and not fname.begins_with("."):
+			result.append(dir_path.path_join(fname))
+		fname = dir.get_next()
+	dir.list_dir_end()
+	return result
+
+func _run_script(path: String) -> RunResult:
+	var r := RunResult.new()
+	var script := load(path)
+	if script == null:
+		push_error("Cannot load: %s" % path)
+		return r
+
+	if not script.has_method("new"):
+		push_error("Cannot instantiate: %s" % path)
+		return r
+
+	var obj = script.new()
+	var methods := _get_test_methods(script)
+
+	print("# Running: %s (%d tests)" % [path, methods.size()])
+
+	for m in methods:
+		var test_name := m.trim_prefix("test_").replace("_", " ").capitalize()
+		r.total += 1
+
+		var ok := true
+		var err_msg := ""
+		var callable = Callable(obj, m)
+		var result = callable.call()
+		if result is String and result.length() > 0:
+			ok = false
+			err_msg = result
+
+		if ok:
+			r.passed += 1
+			print("ok %d - %s" % [r.total, test_name])
+		else:
+			r.failed += 1
+			print("not ok %d - %s" % [r.total, test_name])
+			var file_line := "(unknown)"
+			if obj.has_method("_get_current_line"):
+				file_line = str(obj._get_current_line())
+			r.failures.append("%s::%s: %s" % [path.get_file(), m, err_msg])
+
+	if not obj is RefCounted:
+		obj.free()
+	return r
+
+func _get_test_methods(script: Script) -> Array[String]:
+	var result: Array[String] = []
+	var methods := script.get_script_method_list()
+	for m in methods:
+		var name := m["name"] as String
+		if name.begins_with("test_") and name != "_init":
+			result.append(name)
+	return result