refactor: separate sync domain pipeline

[ClaudiaFang]

Summary

• reduce SyncStatusView to an 11.5 KB composition view with extracted state, pure selectors, renderer, controller, navigator, and operations
• reduce SyncManager to a 13.7 KB facade backed by scanner, planner, push/pull coordinators, focused executors, metadata, conflict, refresh, workspace, and diff services
• establish a SyncWorkspace UI/domain boundary so sync-status UI no longer depends on provider trees, provider settings, or vault mutation helpers
• preserve the historical public API and observable sync behavior
• add focused unit, integration, regression, desktop-path, and mobile-path safety coverage

Scope

Architecture refactor and regression safety only. This deliberately excludes the VS Code-like source-control redesign, diff UI redesign, provider redesign, and sync semantic changes.

Validation

• npx eslint .
• npm run build including Obsidian 1.11 compatibility
• npx vitest run — 54 files / 598 tests
• npm run test:e2e -- --provider gitea — 2 files / 14 tests with container cleanup
• git diff --check

Remaining manual verification

Real Obsidian Desktop and Mobile smoke paths remain to be performed before marking this PR ready for review.

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[ClaudiaFang]

🎉 This PR is included in version 1.5.9 🎉

The release is available on GitHub release

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