Prefer a block signature that declares parameters

[apiology]

A block parameter resolves as undefined when a gem's yardoc and a workspace
@!parse stub both declare a method and only the stub declares the yield:

# in the gem
module Widgetbox
  class << self
    # @return [String]
    def build(&block) = 'x'
  end
end

# in the workspace
# @!parse
#   module Widgetbox
#     class << self
#       # @yieldparam config [String]
#       # @return [String]
#       def build(&block); end
#     end
#   end

Widgetbox.build { |config| config.upcase } # Unresolved call to upcase

ApiMap::Store combines the pins into one carrying two signatures. The gem's
bare &block yields { () -> }, and Chain::Call took the first, never
reading the stub's @yieldparam.

Signatures whose block declares parameters now sort ahead. That changes the
outcome only where both already matched the call's arity and arguments and the
winner was arbitrary.

Two adjacent shapes remain uncovered: a stub without @return, whose
signatures combine_signatures discards as all-undefined, and a gem using
def self.build against a stub using class << self, where the pins never
combine.

Based on castwide#1288, whose store combining produces the two-signature pin. On
master the @!parse pin is discarded by [stack.first].compact before
selection runs, so the two-signature pin does not exist and this sort has
nothing to reorder — the symptom is the same there, by a different mechanism.

This PR was written by Claude Code on behalf of @apiology.