Prepare CallWaveKit 0.4.0 release

[PetrShtuka]

Summary

• switch SwiftPM from the repository-local PJSIP XCFramework to the published checksum-pinned binary release
• close the 0.4.0 changelog and record the physical-device Majordom PBX call validation
• mark the 0.4 release checklist complete while retaining the numbered field scenarios as the regression matrix

Published binary

The immutable PJSIP 2.17 binary prerelease is available at pjsip-2.17-ios15-apple-tls.1. It includes the XCFramework, SHA-256, build manifest, GPLv2 copy, and third-party licences.

SwiftPM checksum: 262e3341dd2d6b4737795902f76a11611709ed3a16908521f1700229e28c6bee

Validation

• SwiftPM downloaded and linked the published asset successfully
• 67 tests pass: 19 Objective-C reliability/registry tests and 48 Swift tests
• generic iOS device build succeeds
• strict Swift concurrency build succeeds
• pod lib lint CallWaveKit.podspec --skip-tests --platforms=ios succeeds without --allow-warnings
• the maintainer confirmed registration and a real incoming call with two-way audio on a physical iPhone through the Majordom PBX

After merge, tag the merge result as 0.4.0, publish the GitHub Release with the binary/checksum/licence assets, and run pod trunk push CallWaveKit.podspec.