refactor(functions): standardize documentation, metadata, and wrappers

- Add comprehensive `--description` flags to all fish functions for better `help` and `functions` output.
- Introduce and correct `--wraps` flags to ensure proper completions for aliased commands (e.g., `top` wrapping `btop`, `zellij`, `upgrade` wrapping `paru`).
- Prepend descriptive comments before function definitions for better source readability.
- Add standard copyright and SPDX license identifiers to shell scripts.
- Enhance script robustness by ensuring consistent terminal checks (Kitty, WezTerm) and graceful fallbacks in window/tab spawning functions (`spwin`, `tab`).
- Implement graceful fallbacks to basic core utilities when preferred modern alternatives are missing (e.g., `top` falling back to system `top` if `btop` is missing, `view` falling back to `less` or `cat` if `nvim` is unavailable).
- Improve overall code consistency across the `functions/` directory.

functions/spwin.fish

@@ -1,10 +1,18 @@
 # Copyright (C) 2026 Rootiest
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-function spwin --wraps='~/.config/kitty/spawn-window.sh' --description 'alias spwin=~/.config/kitty/spawn-window.sh'
-    if test "$TERM" != xterm-kitty
-        echo "Error: The 'spwin' command requires Kitty terminal." >&2
+# spawn window in kitty or wezterm
+function spwin --wraps='~/.config/kitty/spawn-window.sh' --description 'spawn window in kitty or wezterm'
+    if test "$TERM" = xterm-kitty
+        if test -x ~/.config/kitty/spawn-window.sh
+            ~/.config/kitty/spawn-window.sh $argv
+        else
+            kitty @ launch --type=window $argv
+        end
+    else if test "$TERM_PROGRAM" = WezTerm
+        wezterm cli spawn $argv
+    else
+        echo "Error: The 'spwin' command requires Kitty or WezTerm." >&2
         return 1
     end
-    ~/.config/kitty/spawn-window.sh $argv
 end