Add custom #inspect to core classes for console readability

[dhurba87]

Why

All Wreq classes currently use Ruby's default #inspect, which dumps unhelpful output like #<Wreq::Response:0x0000000120b11798> in IRB/Pry. This makes debugging tedious because you can't see status codes, headers, or cookie details at a glance.

What changed

Added #inspect to 7 core classes with compact, informative output:

response.inspect  #=> #<Wreq::Response 200 content-type="application/json" body=1.2KB>
headers.inspect   #=> #<Wreq::Headers [5 headers]>
cookie.inspect    #=> #<Wreq::Cookie sid domain=example.com path=/ secure http_only>
jar.inspect       #=> #<Wreq::Jar [3 cookies]>
client.inspect    #=> #<Wreq::Client>
status.inspect    #=> #<Wreq::StatusCode 200 OK>
version.inspect   #=> #<Wreq::Version HTTP/1.1>

Response#to_s now returns body text (matching HTTP.rb, HTTParty, RestClient conventions), so puts response prints the body rather than the debug summary.

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Note

Medium Risk
Mostly debug/console-output changes, but Response#to_s behavior changes and could affect callers relying on the previous string representation.

Overview
Adds custom #inspect implementations for Wreq::Client, Wreq::Headers, Wreq::Cookie, Wreq::Jar, Wreq::StatusCode, and Wreq::Version to provide compact, non-sensitive console output (e.g., counts/flags vs. dumping object ids or cookie values).

Changes Wreq::Response so to_s now returns the response body (text) and moves the prior compact debug formatting to inspect (including status, optional content-type, and formatted body size). Adds test/inspect_test.rb to cover the new inspect/to_s expectations across these types.

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