chore: bump version to 0.2.0

[jamubc]

Why

Main now carries the multi-platform work (opener plugin, tray number-in-icon, gated uninstall, three-OS release matrix), all unreleased. Version bumps and release prep go through a chore PR per the org standard, and v0.2.0 is the first release to ship Windows and Linux builds.

What Changes

• Bump 0.1.0 to 0.2.0 in package.json, src-tauri/tauri.conf.json, src-tauri/Cargo.toml, and src-tauri/Cargo.lock (the lineage-core crate versions independently).

MODIFIED Requirements

Requirement: Version Lockstep

Every release SHALL carry one version across package.json, tauri.conf.json, Cargo.toml, and Cargo.lock, and the tag MUST match that version.

Scenario: Tagging builds the multi-platform draft

• GIVEN this PR merged to main
• WHEN the annotated tag v0.2.0 is pushed on the merge commit
• THEN the release workflow builds macOS, Windows, and Linux and assembles one draft release with a merged latest.json covering all three platforms

Verification

1. Bump
   1.1 All four version files read 0.2.0 and lineage-core stays 0.1.0.
2. CI
   2.1 The three-OS build workflow passes on this PR.