feat(shell): add bash-style history expansions and interactive keybindings

- Replicate bash bang-operations (!^, !*, !string, etc.) via abbreviations
- Add Ctrl+G for previous path head insertion
- Add Ctrl+F for interactive history substitution
- Add Ctrl+Alt+U to quickly replace command tokens
- Update README documentation for all new features

functions/expand_bang_caret.fish

@@ -0,0 +1,8 @@
+function expand_bang_caret
+    # Split the last history item into a list
+    set -l tokens (string split -n ' ' -- $history[1])
+    # tokens[1] is the command, tokens[2] is the first argument
+    if set -q tokens[2]
+        echo -- $tokens[2]
+    end
+end