chore: bump version to 0.7.0

[jamubc]

Why

Main now carries the multi-platform build work plus the settings wiki, Contexting, and list-nesting features, all unreleased. Version bumps and release prep go through a chore PR per the org standard, and v0.7.0 is the first release to ship Windows and Linux builds.

What Changes

• Bump 0.6.2 to 0.7.0 in package.json, src-tauri/tauri.conf.json, src-tauri/Cargo.toml, and src-tauri/Cargo.lock (via npm run bump).
• Add the ## [0.7.0] CHANGELOG section covering Windows/Linux support, the settings wiki with Contexting, Tab list nesting, titlebar theme sync, and the palette long-title fix.

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. The CHANGELOG section for the tag becomes the release notes and the in-app updater's "What's new" text, so it MUST describe this release for users.

Scenario: Tagging builds the multi-platform draft

• GIVEN this PR merged to main
• WHEN the annotated tag v0.7.0 is pushed on the merge commit
• THEN the release workflow builds macOS, Windows, and Linux, assembles one draft release with a merged latest.json, and uses this CHANGELOG section as the notes

Verification

1. Bump
   1.1 git grep -l "0\.7\.0" -- package.json src-tauri/tauri.conf.json src-tauri/Cargo.toml src-tauri/Cargo.lock lists all four files.
   1.2 The CHANGELOG gains a ## [0.7.0] - 2026-07-06 section and [Unreleased] stays empty.
2. CI
   2.1 The three-OS build workflow passes on this PR.