feat(fish-deps): add uv as managed dep; install before cargo and fish

uv is now listed first in the catalog (before cargo and fish) so it is
installed automatically before the fish source build is attempted.
Install uses the official curl script; update uses `uv self update`.

Catalog order is now: uv → cargo → fish → … ensuring prerequisites are
in place before any dependent install method runs.

README updated: uv and cargo added to the Required table, warning callout
and dependency management note reflect the automatic install flow.

functions/_fish_deps_install.fish

@@ -47,6 +47,9 @@ function _fish_deps_install
 
             # Preferred special methods — listed before system PM so they are the default
             switch $special
+                case curl-uv
+                    set -a methods special-uv
+                    set -a method_labels "curl installer (official script)"
                 case git-cargo-fish
                     if type -q cargo; and type -q uv
                         set -a methods special-git-cargo-fish
@@ -206,6 +209,20 @@ function _fish_deps_install
                     and makepkg -si --noconfirm
                     and popd
                     rm -rf $_build_dir
+                case special-uv
+                    curl -LsSf https://astral.sh/uv/install.sh | sh
+                    # Add uv to PATH for the rest of this session
+                    for _d in "$HOME/.local/bin" "$HOME/.cargo/bin"
+                        if test -d "$_d"
+                            fish_add_path "$_d"
+                            break
+                        end
+                    end
+                    if not type -q uv
+                        set_color yellow
+                        echo "  uv not yet in PATH — restart your shell if subsequent installs fail."
+                        set_color normal
+                    end
                 case special-git-cargo-fish
                     set -l _tmpdir (mktemp -d)
                     set -l _build_ok 0