feat: add git and history utility functions

- Add branch, fc, and gitup functions
- Update README documentation for new functions and abbreviations
- Remove obsolete push-vim function

functions/fc.fish

@@ -0,0 +1,37 @@
+function fc --description "Edit and execute the last command (Bash-style fc)"
+    set -l tmpfile (mktemp /tmp/fish_fc.XXXXXX).fish
+
+    if count $argv >/dev/null
+        # Search for a specific previous command
+        builtin history search --max=1 "$argv" | sed 's/^[0-9-]* [0-9:]* //' >$tmpfile
+    else
+        # Grab the last 2 commands, then take the 2nd one (the one before 'fc')
+        # This avoids the --skip flag entirely
+        builtin history --max=2 | sed 's/^[0-9-]* [0-9:]* //' | sed -n 2p >$tmpfile
+    end
+
+    # Set editor with fallback
+    set -l editor $EDITOR
+    if test -z "$editor"
+        set editor vi
+    end
+
+    # Only open editor if we actually got a command
+    if test -s $tmpfile
+        $editor $tmpfile
+
+        # Final check if user cleared the file in the editor
+        if test -s $tmpfile
+            set -l command (cat $tmpfile)
+            rm $tmpfile
+            commandline -r "$command"
+            commandline -f execute
+        else
+            rm $tmpfile
+            echo "fc: Aborted (empty file)"
+        end
+    else
+        rm $tmpfile
+        echo "fc: Could not retrieve history"
+    end
+end