feat(fish): ✨ Add helix key bindings from https://github.com/sshilovsky/fish-helix/tree/main

Add comprehensive helix-like modal key bindings system for fish shell
with:
- New `fish_helix_key_bindings` function with helix-inspired navigation
- Modal editing support with count modifiers via `fish_bind_count`
- Visual mode prompt indicator via `fish_default_mode_prompt`
- Enhanced clipboard integration with proper notification formatting

The implementation provides vim/helix-style modal editing while
maintaining
fish shell compatibility and includes proper mode indicators, count
tracking,
and seamless integration with existing fish key binding systems.

home/.config/fish/functions/fish_default_mode_prompt.fish

@@ -0,0 +1,26 @@
+function fish_default_mode_prompt --description "Display vi/helix prompt mode"
+    # Do nothing if not in vi mode
+    if test "$fish_key_bindings" = fish_vi_key_bindings
+        or test "$fish_key_bindings" = fish_helix_key_bindings
+        or test "$fish_key_bindings" = fish_hybrid_key_bindings
+        switch $fish_bind_mode
+            case default
+                set_color --bold red
+                echo '[N]'
+            case insert
+                set_color --bold green
+                echo '[I]'
+            case replace_one
+                set_color --bold green
+                echo '[R]'
+            case replace
+                set_color --bold cyan
+                echo '[R]'
+            case visual
+                set_color --bold magenta
+                echo '[V]'
+        end
+        set_color normal
+        echo -n ' '
+    end
+end