config(fish): add fish completions for cli tools

dot_config/fish/functions/ghg.fish

@@ -0,0 +1,18 @@
+function ghg -a repo
+    # ghq natively understands https://, ssh://, git@host:…, and host/user/repo
+    ghq get $repo; or return
+
+    # Reduce the input to ghq's on-disk shape: <host>/<user>/<repo>
+    set -l rel (string replace -r '^\w+://' '' -- $repo)   # strip scheme  (https://, ssh://, git://)
+    set rel (string replace -r '^[^@/]+@' '' -- $rel)       # strip user@   (git@github.com:…)
+    set rel (string replace ':' '/' -- $rel)                # scp host:path → host/path
+    set rel (string replace -r '\.git$' '' -- $rel)         # strip trailing .git
+
+    # bare "user/repo" with no host → default to github.com
+    string match -q '*.*/*' -- $rel; or set rel github.com/$rel
+
+    set -l dir (ghq root)/$rel
+    cd $dir; or return
+    zoxide add $dir
+    clear; and onefetch
+end