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_search.fish

@@ -0,0 +1,21 @@
+function expand_bang_search
+    set -l token $argv[1]
+    if test -z "$token"
+        set token (commandline -t)
+    end
+    
+    # Extract query: looks for text after !? and before an optional ?
+    set -l query (string match -r '!\?([^?]+)' -- $token)[2]
+    
+    if test -n "$query"
+        # Search history for a match anywhere in the command
+        set -l match (builtin history search --contains --max=1 -- $query)
+        
+        if test -n "$match"
+            echo -- $match
+            return
+        end
+    end
+    
+    echo -- $token
+end