Update documentation, CHANGELOG, and version for v1.0.0

[kcenon]

What

Update all version references, CHANGELOG, and documentation to reflect v1.0.0 release.

Part of #670

Why

• Current version is 0.3.1 across 5 locations — must be updated to 1.0.0
• README claims 72% code coverage but actual may differ — needs verification
• CHANGELOG needs a v1.0.0 section summarizing all changes since 0.3.1
• FetchContent examples pin to v0.3.0 — users need correct v1.0.0 reference

Where

Version Locations

File	Current	Target
CMakeLists.txt:15	VERSION 0.3.1	VERSION 1.0.0
vcpkg.json:4	"version-semver": "0.3.1"	"version-semver": "1.0.0"
README.md:412	GIT_TAG v0.3.0	GIT_TAG v1.0.0
README.md:39	"72% code coverage"	Actual verified value

Documentation Files

• CHANGELOG.md — add v1.0.0 section
• README.md — version refs, coverage claim, v1.0 API guarantees section

How

Technical Approach

1. Verify actual code coverage percentage
2. Update version numbers in all 5 locations
3. Create CHANGELOG v1.0.0 section summarizing: queue consolidation, hazard pointers, lock-free MPMC, error handling migration
4. Update README coverage claim to verified value
5. Add v1.0 API stability guarantees section to README
6. Update FetchContent/vcpkg examples with v1.0.0

Acceptance Criteria

• All version references updated to 1.0.0
• CHANGELOG has complete v1.0.0 section in keep-a-changelog format
• README coverage claim matches actual measured value
• FetchContent example pins to v1.0.0
• No stale version references remain

[kcenon]

Implementation Update

Field	Value
PR	#678
Branch	docs/issue-673-update-documentation-changelog-and-version-for-v1
Status	In Review

Summary

Updated all 16 files: version bump to 1.0.0 (CMakeLists.txt, vcpkg.json), CHANGELOG v1.0.0 section, corrected code coverage from 72% to 49% (Codecov-verified), and updated all FetchContent/doc version references.