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/bd-pull.fish

@@ -1,12 +1,13 @@
 # Copyright (C) 2026 Rootiest
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-function bd-pull -d "Pull new Gitea issues into local Beads and link them"
+# Pull new Gitea issues into local Beads and link them
+function bd-pull --description 'Pull new Gitea issues into local Beads and link them'
     if not set -q argv[1]; echo "Need repo owner/name"; return 1; end
     if not set -q GITEA_TOKEN; echo "\$GITEA_TOKEN not set"; return 1; end
 
     set -l REPO $argv[1]
-    set -l GITEA_URL "https://git.rootiest.dev"
+    if not set -q GITEA_URL; echo "\$GITEA_URL not set"; return 1; end
     set -l IMPORT_COUNT 0
 
     echo (set_color blue)"📡 Checking Gitea: $REPO..."(set_color normal)