Add configured client copies with request and response callbacks

[dblock]

Usage

observed = client.with_request do |request|
  request.headers["X-Custom"] = "value"
end
observed = observed.with_response do |response|
  scopes = response.headers["x-oauth-scopes"]&.split(",")&.map(&:strip)
end

result = observed.auth_test
observed.users_list do |page|
  puts page.members
end

Behavior

• Both methods return configured client copies with independent connections; the original is unchanged.
• Callbacks cover every HTTP request, including pagination and helper calls. Existing return values and endpoint blocks are unchanged.
• Request callbacks run after request configuration and before dispatch. Response callbacks run after successful completion with parsed body, headers, and status.
• Chaining appends callbacks in registration order. Callback exceptions propagate; response callbacks do not run on Slack or transport errors.
• No generator, generated endpoint, or patch-file changes are needed with this revised design.

Validation

632 non-CLI specs pass and RuboCop reports no offenses. CLI specs remain excluded locally because an existing Bundler warning contaminates subprocess output. Existing submodule changes are excluded.

Follow-up to #382. Prepared by an AI on behalf of @dblock.

[github-actions]

Danger Report

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[coveralls]

Coverage Report for CI Build 37312481885

Warning

Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes.
Quick fix: rebase this PR. Learn more →

Coverage increased (+0.1%) to 91.178%

Details

• Coverage increased (+0.1%) from the base build.
• Patch coverage: 92 of 92 lines across 3 files are fully covered (100%).
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	6087
Covered Lines:	5550
Line Coverage:	91.18%
Coverage Strength:	102.83 hits per line

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💛 - Coveralls