fix(first-run): move fish-config.1 symlink install to first-run

Startup side-effects that modify the filesystem belong in first-run, not
in a recurring conf.d fragment. The symlink is now created once (like a
real install step) instead of being checked on every shell launch.

MANPATH addition stays in tricks.fish — that's an env var that must be
set each session.

conf.d/tricks.fish

@@ -17,16 +17,10 @@ end
 fish_add_path ~/.local/bin
 fish_add_path ~/Applications/depot_tools
 
-# Expose user-local man pages and keep fish-config.1 symlink current
+# Expose user-local man pages
 if not contains ~/.local/share/man $MANPATH
     set -gx MANPATH ~/.local/share/man $MANPATH
 end
-set -l _man1 ~/.local/share/man/man1
-set -l _src ~/.config/fish/docs/fish-config.1
-if test -f $_src; and not test -L $_man1/fish-config.1
-    mkdir -p $_man1
-    ln -sf $_src $_man1/fish-config.1
-end
 
 # Format man pages using bat (only if bat is installed)
 # Overriding $MANPAGER is opinionated (C3 overrides)