Prepare changelog for first beta

[Zhortein]

Objective

Prepare CHANGELOG.md for the first beta release.

Target version

v0.3.0-beta.1

Scope

• Review the Unreleased section.
• Ensure all changes since v0.2.0-alpha.1 are listed.
• Include:
  • bulk actions and row selection;
  • icon system and visual consistency;
  • advanced filter expressions / search builder;
  • smoke-test fixes;
  • docs updates;
  • any dependency/CI changes.
• Ensure no unimplemented feature is listed as implemented.
• Prepare or verify release notes extraction.

Acceptance criteria

• CHANGELOG.md is accurate.
• Target version is confirmed.
• Release notes can be extracted.
• QA passes.