feat(shell): add scrollback history capture on shell exit

- Add smart_exit function: captures Kitty scrollback to a timestamped
  log file on exit; --no-log/-n skips capture; auto-prunes oldest logs
  once count exceeds SCROLLBACK_HISTORY_MAX_FILES
- Wire exit → smart_exit in config.fish for interactive sessions;
  export SCROLLBACK_HISTORY_DIR and SCROLLBACK_HISTORY_MAX_FILES with
  sane defaults (~/.terminal_history and 100 respectively)
- Update cat to detect files in SCROLLBACK_HISTORY_DIR or containing
  raw ANSI escape sequences and pass them through command cat instead
  of bat, preserving color output
- Remove redundant alias rm="rm -i" from tricks.fish (superseded by
  functions/rm.fish trash-aware wrapper)
- Sync README: new Scrollback History integration section, smart_exit
  added to System functions table, cat description updated, stale rm
  Safety Wrapper entry and note removed

functions/cat.fish

@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
 # Use bat for files and ls for directories when using cat
-function cat --wraps='bat' --description 'Use bat for files and ls for directories'
+function cat --wraps='bat' --description 'Use bat for files, ls for directories, and raw cat for ANSI logs'
     # If no arguments are provided, cat usually waits for stdin. 
     # We'll maintain that behavior by skipping the directory check if $argv is empty.
     if set -q argv[1]
@@ -11,6 +11,16 @@ function cat --wraps='bat' --description 'Use bat for files and ls for directori
             ls $argv
             return
         end
+
+        # NEW: Check if the target file lives in your scrollback snapshot directory OR 
+        # contains raw terminal ANSI color escape sequences.
+        if test -f $argv[1]
+            if string match -q "$SCROLLBACK_HISTORY_DIR/*" $argv[1]
+                or string match -qr '\e\[[0-9;]*m' (head -n 5 $argv[1] 2>/dev/null)
+                command cat $argv
+                return
+            end
+        end
     end
 
     # Fallback to bat or standard cat