config(fish): add fish completions for cli tools

dot_config/fish/functions/extract_agents.fish

@@ -0,0 +1,18 @@
+function extract_agents -d "Copy all AGENTS.md files to a target directory while preserving structure"
+    set -l out_dir $argv[1]
+
+    # Validate input
+    if test -z "$out_dir"
+        echo "Error: Output directory required."
+        echo "Usage: extract_agents <absolute_or_relative_output_path>"
+        return 1
+    end
+
+    # Ensure output directory exists
+    mkdir -p $out_dir
+
+    # Find and copy preserving relative paths
+    fd -t f -g "AGENTS.md" -x cp --parents "{}" $out_dir
+
+    echo "Extraction complete. Check $out_dir."
+end