Bump release metadata to 1.3.0 and align docs/changelog with the latest feature PR

[Copilot]

This updates the project release metadata and release-facing documentation to match the latest merged feature work. It bumps the next published version and refreshes the changelog/README so the release story reflects the current product surface.

• Version metadata

  • Bumps the canonical project version from 1.2.0 to 1.3.0
  • Keeps Rust and package metadata aligned across:
    • Cargo.toml
    • package.json

• Changelog

  • Adds a new 1.3.0 entry summarizing the last PR’s major user-facing changes:
    • 3D UI and interaction upgrades
    • native installer/release packaging additions
    • background update support
    • optimizer/backend architecture and heuristic improvements
    • CI/release pipeline expansion

• README refresh

  • Updates the feature summary to surface the capabilities added in the last PR:
    • physics-aware packing heuristics
    • native installers (.deb, .pkg, .msix)
    • GitHub release updater
  • Updates the release tag example to use the new version (v1.3.0)

# Cargo.toml
version = "1.3.0"

// package.json
"version": "1.3.0"

---

📍 Connect Copilot coding agent with Jira, Azure Boards or Linear to delegate work to Copilot in one click without leaving your project management tool.

[Copilot]

Pull request overview

This PR bumps the project’s release version to 1.3.0 and updates release-facing documentation (README + CHANGELOG) so the published release notes match the current feature set across the Rust backend, web UI, and packaging/update tooling.

Changes:

• Bumped version metadata from 1.2.0 → 1.3.0 in Cargo.toml and package.json.
• Refreshed README.md feature bullets and installation tag example to reflect the latest capabilities.
• Added a 1.3.0 entry to CHANGELOG describing the recent UI, packaging, updater, and backend improvements.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
package.json	Updates npm/package metadata version to 1.3.0.
Cargo.toml	Updates Rust crate version to 1.3.0.
README.md	Updates feature summary and example release tag to v1.3.0.
CHANGELOG	Adds a new 1.3.0 release entry summarizing recent user-facing changes.