Rework TUI: single-threaded curses, scrollback buffer, server menu

- All curses drawing on the main thread; stdin polled together with the
  ZMQ sockets, Ctrl-C only sets a flag
- Output kept in a 2000-line buffer and redrawn from it, so resizes keep
  the history; PgUp/PgDn and mouse wheel scroll it
- Messages without trailing newline continue the current line (status
  table columns arrive as separate messages)
- Too-small terminal shows a warning instead of exiting
- Start without arguments shows a server selection menu
- Colors on the terminal default background; version 0.9.0

lib/constants.py

@@ -5,7 +5,7 @@ Configuration and constants for QLPyCon
 
 import re
 
-VERSION = "0.8.1"
+VERSION = "0.9.0"
 
 # Pattern matching
 COLOR_CODE_PATTERN = re.compile(r'\^\d')  # Quake color codes (^0-^9)
@@ -21,10 +21,13 @@ RESPAWN_DELAY = 3.0  # Seconds before players respawn after death
 STATS_CONNECTION_DELAY = 0.5  # Initial stats connection delay
 
 # UI dimensions
+MIN_ROWS = 20
+MIN_COLS = 80
 INFO_WINDOW_HEIGHT = 12
 INFO_WINDOW_Y = 2
 OUTPUT_WINDOW_Y = 14
 INPUT_WINDOW_HEIGHT = 2
+OUTPUT_SCROLLBACK_LINES = 2000  # Output lines kept for PgUp/PgDn and redraw after resize
 
 # Event deduplication
 MAX_RECENT_EVENTS = 10