Fix ruff lint errors across matrixbot (F401, F841, E402)

Remove unused imports: logging from bot.py and config.py, RoomMessageText/
UnknownEvent from callbacks.py, functools.partial and MAX_INPUT_LENGTH from
commands.py. Rename unused local variables to _ (resp in cmd_ping, symbols in
render_keyboard_plain, guesses_left in two wordle functions). Move wordle import
to top of commands.py to fix E402.

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

matrixbot/commands.py

@@ -6,16 +6,16 @@ import time
 import logging
 from collections import Counter
 from datetime import datetime
-from functools import partial
 
 import aiohttp
 
 from nio import AsyncClient
 
 from utils import send_text, send_html, send_reaction, sanitize_input
+from wordle import handle_wordle
 from config import (
     MAX_DICE_SIDES, MAX_DICE_COUNT, BOT_PREFIX, ADMIN_USERS,
-    OLLAMA_URL, OLLAMA_MODEL, MAX_INPUT_LENGTH, COOLDOWN_SECONDS,
+    OLLAMA_URL, OLLAMA_MODEL, COOLDOWN_SECONDS,
     MINECRAFT_RCON_HOST, MINECRAFT_RCON_PORT, MINECRAFT_RCON_PASSWORD,
     RCON_TIMEOUT, MIN_USERNAME_LENGTH, MAX_USERNAME_LENGTH,
 )
@@ -99,7 +99,7 @@ async def cmd_help(client: AsyncClient, room_id: str, sender: str, args: str):
 @command("ping", "Check bot latency")
 async def cmd_ping(client: AsyncClient, room_id: str, sender: str, args: str):
     start = time.monotonic()
-    resp = await send_text(client, room_id, "Pong!")
+    _ = await send_text(client, room_id, "Pong!")
     elapsed = (time.monotonic() - start) * 1000
     # Edit isn't straightforward in Matrix, so just send a follow-up if slow
     if elapsed > 500:
@@ -822,8 +822,6 @@ async def cmd_health(client: AsyncClient, room_id: str, sender: str, args: str):
 # ---------------------------------------------------------------------------
 # Wordle
 # ---------------------------------------------------------------------------
-from wordle import handle_wordle
-
 
 @command("wordle", "Play Wordle! (!wordle help for details)")
 async def cmd_wordle(client: AsyncClient, room_id: str, sender: str, args: str):