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/tab.fish

@@ -1,7 +1,21 @@
 # Copyright (C) 2026 Rootiest
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-function tab --wraps='konsole --new-tab --workdir "$cdto"' --description 'alias tab=konsole --new-tab --workdir "$cdto"'
-  konsole --new-tab --workdir "$cdto" $argv
-        
+# Spawn a new tab in the current terminal
+function tab --description 'Spawn a new tab in the current terminal'
+    set -l dir "$cdto"
+    if test -z "$dir"
+        set dir "$PWD"
+    end
+
+    if test "$TERM" = xterm-kitty
+        kitty @ launch --type=tab --cwd="$dir" $argv
+    else if test "$TERM_PROGRAM" = WezTerm
+        wezterm cli spawn --cwd "$dir" $argv
+    else if set -q KONSOLE_VERSION
+        konsole --new-tab --workdir "$dir" $argv
+    else
+        echo "Error: No supported terminal found. Try Kitty, WezTerm, or Konsole." >&2
+        return 1
+    end
 end