Add Matrix bot Phase 1: core setup + fun commands

Modular bot using matrix-nio[e2e] with E2EE support, deployed as
systemd service on Synapse LXC. Includes 10 commands: help, ping,
8ball, fortune, flip, roll, random, rps, poll, champion.

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

config.py

@@ -0,0 +1,34 @@
+import os
+import logging
+from dotenv import load_dotenv
+
+load_dotenv()
+
+
+# Required
+MATRIX_HOMESERVER = os.getenv("MATRIX_HOMESERVER", "https://matrix.lotusguild.org")
+MATRIX_USER_ID = os.getenv("MATRIX_USER_ID", "@lotusbot:matrix.lotusguild.org")
+MATRIX_ACCESS_TOKEN = os.getenv("MATRIX_ACCESS_TOKEN", "")
+MATRIX_DEVICE_ID = os.getenv("MATRIX_DEVICE_ID", "")
+
+# Bot settings
+BOT_PREFIX = os.getenv("BOT_PREFIX", "!")
+ADMIN_USERS = [u.strip() for u in os.getenv("ADMIN_USERS", "").split(",") if u.strip()]
+LOG_LEVEL = os.getenv("LOG_LEVEL", "INFO")
+
+# Constants
+MAX_INPUT_LENGTH = 500
+MAX_DICE_SIDES = 100
+MAX_DICE_COUNT = 20
+
+
+class ConfigValidator:
+    REQUIRED = ["MATRIX_HOMESERVER", "MATRIX_USER_ID", "MATRIX_ACCESS_TOKEN", "MATRIX_DEVICE_ID"]
+
+    @classmethod
+    def validate(cls):
+        errors = []
+        for var in cls.REQUIRED:
+            if not os.getenv(var):
+                errors.append(f"Missing required: {var}")
+        return errors