chore: release v0.2.0

[asphaltbuffet]

Release v0.2.0

Updates CHANGELOG.md with the v0.2.0 release notes.

After merging, create the release tag from main by running:

mise run release minor

This will:

1. Compute v0.2.0 from the current v0.1.0 tag
2. Verify the changelog entry exists
3. Create and push the annotated v0.2.0 tag to origin
4. Trigger the goreleaser GitHub Actions release workflow

What's in this release

• Unified entity model (items + locations → entities)
• New serve command with local web UI
• New rename and status commands
• New internal/app, internal/store, internal/eventbus, internal/inventory, internal/entitypath packages
• All commands migrated to the new *app.App architecture
• Squashed migrations to a single initial schema
• Removed legacy cmd/migrate and internal/database packages