docs: credit Omar Aljarrah in LICENSE and showcase the SDK in README

[Wahbeh-Mohammad]

What and why

This PR brings the root LICENSE and README.md in line with the Node SDK's (dexpace/nodejs-sdk).

• LICENSE: the copyright line now reads Copyright (c) 2026 dexpace and Omar Aljarrah, and the wording and wrapping match Node's. All six gems/*/LICENSE copies are updated too, so they stay byte-identical to the root file.
• README: restructured on the Node README's layout:
  • badges, the pre-release status, the gem table and a Gemfile install snippet
  • a quick start: a minimal request, a JSON POST, Pipeline.standard with a bearer-auth step, request bodies, pagination, SSE, three-state PATCH and the async path
  • the sixteen-stage architecture diagram and the layers
  • a table of the dexpace-core namespaces
  • highlights, development, conventions, the release blockers and the license

CODE_OF_CONDUCT.md, CONTRIBUTING.md and SECURITY.md already follow Node's versions section for section, so they are unchanged.

Requirements

None. This is documentation and licensing only.

Verification

• rake gates:reproducible and gates:gemspec_audit are green, and test/gates/gem_layout_test.rb passes (per-gem LICENSE byte-identity), on Ruby 4.0.6
• A test that failed before this change and passes after it: n/a
• sig/ and the surface snapshot: n/a, no public surface change
• ruby .claude/skills/housekeeping/probe.rb exits 0
• Every README example was run under ruby -w on 4.0.6 against a local HTTP server. The auth example ran over a fake https transport instead, because the AUTH step refuses plaintext.

The full bundle exec rake was not run locally.

Records

• No deviation
• No release work uncovered or closed
• The as-built pages and gem READMEs are unchanged and still describe the code
• Nothing under docs/product-spec/ or docs/sdk-design-ruby/ was edited