feat(help): header-driven --help for listing presets

lD, lsr, lss, lstree, lt, ltr, lx and ld. None shadows a real binary, so
there is no disabled-fallback contract to honour, and `eza --help`
documented eza rather than the preset that is these functions' entire
content. First-arg-only interception leaves `lt -la --help` passing
through to eza untouched.

functions/lD.fish

@@ -17,6 +17,8 @@
 # EXAMPLE
 #   lD ~/projects
 function lD --description 'List directories only'
+    __fish_help_header (status current-function) $argv; and return 0
+
     if which eza >/dev/null 2>&1
         eza --only-dirs --long --icons --color=auto --hyperlink $argv
     else if which lsd >/dev/null 2>&1

functions/ld.fish

@@ -17,6 +17,8 @@
 # EXAMPLE
 #   ld
 function ld --description 'Run lazydocker on the current Docker context'
+    __fish_help_header (status current-function) $argv; and return 0
+
     if not type -q docker
         echo "ld: docker is not installed" >&2
         return 1

functions/lsr.fish

@@ -17,6 +17,8 @@
 # EXAMPLE
 #   lsr ~/projects
 function lsr --description 'Reversed time-sorted listing'
+    __fish_help_header (status current-function) $argv; and return 0
+
     if which eza >/dev/null 2>&1
         eza --oneline --sort=modified --reverse --icons --color=auto --hyperlink $argv
     else if which lsd >/dev/null 2>&1

functions/lss.fish

@@ -17,6 +17,8 @@
 # EXAMPLE
 #   lss ~/downloads
 function lss --description 'Size-sorted listing'
+    __fish_help_header (status current-function) $argv; and return 0
+
     if which eza >/dev/null 2>&1
         eza --oneline --long --all --sort=size --icons --color=auto --hyperlink --color-scale=size --color-scale-mode=gradient $argv
     else if which lsd >/dev/null 2>&1

functions/lstree.fish

@@ -17,6 +17,8 @@
 # EXAMPLE
 #   lstree ~/projects/myapp
 function lstree --description 'Full recursive tree listing'
+    __fish_help_header (status current-function) $argv; and return 0
+
     if which eza >/dev/null 2>&1
         eza --tree --icons --color=auto --hyperlink=auto $argv
     else if which lsd >/dev/null 2>&1

functions/lt.fish

@@ -17,6 +17,8 @@
 # EXAMPLE
 #   lt ~/projects
 function lt --description 'Tree listing, depth 2'
+    __fish_help_header (status current-function) $argv; and return 0
+
     if which eza >/dev/null 2>&1
         eza --tree --level=2 --icons --color=auto --hyperlink $argv
     else if which lsd >/dev/null 2>&1

functions/ltr.fish

@@ -18,6 +18,8 @@
 # EXAMPLE
 #   ltr ~/projects
 function ltr --description 'Reversed time-sorted listing'
+    __fish_help_header (status current-function) $argv; and return 0
+
     if which eza >/dev/null 2>&1
         eza --long --all --sort=modified --icons --hyperlink --color=auto --color-scale=age --color-scale-mode=gradient $argv
     else if which lsd >/dev/null 2>&1

functions/lx.fish

@@ -17,6 +17,8 @@
 # EXAMPLE
 #   lx ~/projects
 function lx --description 'Extension-sorted listing'
+    __fish_help_header (status current-function) $argv; and return 0
+
     if which eza >/dev/null 2>&1
         eza --long --all --sort=extension --icons --color=auto --hyperlink $argv
     else if which lsd >/dev/null 2>&1