Rename ASDF systems/packages to io.github.cl-sdk.xml* and align .asd filenames/docs

[Copilot]

This updates the project from the temporary cl-* naming to canonical io.github.cl-sdk.xml* names across systems, packages, and docs. It also makes .asd filenames match their system names for consistent ASDF discovery/loading.

• System + file namespace migration

  • Renamed all ASDF systems:
    • cl-xml → io.github.cl-sdk.xml
    • cl-xml.test → io.github.cl-sdk.xml.test
    • cl-soap / cl-wsdl / cl-xsd (+ .test) → io.github.cl-sdk.{soap,wsdl,xsd} (+ .test)
  • Renamed .asd files to match system names (e.g. io.github.cl-sdk.xml.asd, io.github.cl-sdk.soap.test.asd, etc.).

• Common Lisp package rename

  • Renamed package definitions and in-package forms to io.github.cl-sdk.xml*.
  • Updated all package-qualified symbol usage in source/tests from cl-xml:/cl-soap:/cl-wsdl:/cl-xsd: to the new package prefixes.

• Loader + documentation alignment

  • Updated test runner quickload target to :io.github.cl-sdk.xml.test.
  • Updated README installation/examples to use io.github.cl-sdk.xml naming.

;; before
(defsystem #:cl-xml ...)
(defpackage #:cl-xml ...)
(ql:quickload "cl-xml")

;; after
(defsystem #:io.github.cl-sdk.xml ...)
(defpackage #:io.github.cl-sdk.xml ...)
(ql:quickload "io.github.cl-sdk.xml")