Fix/key sequences (#2)

* Change default hotkey to Ctrl+6 and fix ctrl+punctuation handling
* Disable lookback mode when alternate screen is active

README.md

@@ -52,7 +52,7 @@ claude-chill -l 50 -- claude       # Set max lines to 50
 
 ## Lookback Mode
 
-Press `Ctrl+Shift+J` (or your configured key) to enter lookback mode:
+Press `Ctrl+6` (or your configured key) to enter lookback mode:
 
 1. **Claude pauses** - Output from Claude is cached, input is blocked
 2. **History dumps** - The full history buffer is written to your terminal
@@ -68,7 +68,7 @@ Create `~/.config/claude-chill.toml`:
 ```toml
 max_lines = 100        # Lines shown per sync block
 history_lines = 100000 # Lines stored for lookback
-lookback_key = "[ctrl][shift][j]"
+lookback_key = "[ctrl][6]"
 ```
 
 ### Key Format
@@ -79,6 +79,10 @@ Modifiers: `[ctrl]`, `[shift]`, `[alt]`
 
 Keys: `[a]`-`[z]`, `[f1]`-`[f12]`, `[pageup]`, `[pagedown]`, `[home]`, `[end]`, `[enter]`, `[tab]`, `[space]`, `[esc]`
 
+### Why Ctrl+6?
+
+`Ctrl+6` sends 0x1E, a control character not frequently used by terminals, signals, or shells. Avoid `Ctrl+letter` hotkeys - terminals can't distinguish `Ctrl+J` from `Ctrl+Shift+J`.
+
 ## Disclaimer
 
 This tool was developed for personal convenience on Debian Linux. It works for me, but it hasn't been extensively tested across different terminals, operating systems, or edge cases. Don't use it to send anyone to space, perform surgery, or run critical infrastructure. If it breaks, you get to keep both pieces.