Refine settings navigation and localization

[boycez]

Description

Reorganizes the settings experience into a clearer navigation structure, brings channel management into Settings, and improves first-run localization and product naming consistency.

Related Issue

N/A

Changes

• Consolidate theme controls into General, replace Workspace with a dedicated Gateway section, and preserve legacy settings routes through section normalization.
• Move channel management under Settings, redirect the former /phone route, and align the embedded Channels UI with settings typography and layout.
• Simplify gateway status, restart, port, and log controls while standardizing labels, descriptions, icons, and typography across settings sections.
• Initialize the saved language from the OS locale on first run, with English fallback and unit coverage for Chinese locale variants.
• Use the MicroClaw product name consistently in the window title, tray tooltip, About section, and localized strings.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• CI/CD or build configuration change
• Refactoring (no functional changes)

Testing

• Tests pass locally (cd desktop && npm run test) - 590 tests passed
• Renderer tests pass locally (cd desktop/renderer && npm run test) - 141 tests passed
• Build succeeds (cd desktop && npm run build)
• Manual testing performed (describe below)

Automated tests and a production build were run while preparing this PR. No additional manual test pass was performed.

Checklist

• My code follows the coding guidelines of this project
• I have performed a self-review of my code
• I have commented my code where necessary
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or my feature works
• New and existing unit tests pass locally with my changes