refactor: replace lazy zoxide with eager init and add fd-based directory discovery

- Switch from lazy-loaded z/zi to eager zoxide initialization in config.fish
- Alias cd to use zoxide for automatic frecency tracking
- Add Alt+D: discover directories from git root/cwd with fd+fzf (no gitignore)
- Add Alt+Shift+D: discover directories from HOME with fd+fzf (depth 5)

home/dot_config/fish/functions/zi.fish

@@ -1,24 +1,15 @@
-# Lazy-load zoxide on first use of zi command
+# Interactive zoxide with fzf (initialization handled in config.fish)
 function zi --description "zoxide interactive smart cd"
-    # Initialize zoxide only once (shared flag with z.fish)
-    if not set -q __zoxide_initialized
-        set -g __zoxide_initialized 1
-
-        # Configure fzf options for zoxide interactive mode
-        set -gx _ZO_FZF_OPTS '
+    # Configure fzf options for zoxide interactive mode
+    set -gx _ZO_FZF_OPTS '
   --preview="lsd -1 --color=always --icon=always {2..}"
   --preview-window=down,30%
 '
 
-        # Run zoxide init
-        if command -q zoxide
-            zoxide init fish | source
-        else
-            echo "zoxide is not installed" >&2
-            return 1
-        end
+    if command -q zoxide
+        __zoxide_zi $argv
+    else
+        echo "zoxide is not installed" >&2
+        return 1
     end
-
-    # Execute the actual zi command (defined by zoxide init)
-    __zoxide_zi $argv
 end