Prefer a block signature that declares parameters

[apiology]

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

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

# @!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 both docs into one pin with two signatures;
Chain::Call took the bare &block first, missing the stub's @yieldparam.

Signatures whose block declares parameters now sort ahead, changing outcomes
only where the winner was already arbitrary.

Two shapes remain uncovered: a stub without @return, and def self.build
with class << self, whose pins never combine. Needs castwide#1288's combining;
master discards the pin earlier, so nothing reorders.

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

[apiology]

Claude: Closed in favor of a fix at the actual root cause — combine_signatures_by_type_arity buckets block signatures apart before any merge is attempted, rather than picking between them at call time as this PR did. That fix landed as #94, which was folded into castwide#1288.