feat(home): add file, ripgrep, fd, tree, unzip; remove dead ka alias

modules/home.nix

@@ -183,6 +183,11 @@ in
                 # standalone CPython via nix-ld (see modules/nixos.nix).
     htop        # process viewer; config in ~/.config/htop (XDG-native)
     highlight   # `ccat` alias: syntax-highlighted cat
+    file        # identify file type by content
+    ripgrep     # `rg`: fast recursive grep
+    fd          # fast, ergonomic find
+    tree        # recursive directory listing
+    unzip       # extract .zip (tools that shell out to it expect the binary)
     jq          # JSON on the command line (scripts, ad-hoc inspection)
     pv          # pipe progress meter (throughput, ETA on streamed data)
     libreoffice
@@ -399,7 +404,6 @@ in
       grep = "grep --color=auto";
       diff = "diff --color=auto";
       ccat = "highlight --out-format=ansi";
-      ka = "killall";
       g = "git";
       e = editor;
       v = editor;