fix(desktop): relocate macOS data and compact titlebar

[Luhaozhu]

Summary / 概述

Maintainer CE sync derived from upstream commit 127dac58 with scripts/build_ce.py.

This fixes two macOS desktop issues:

• Store persistent HugAgentOS data under ~/.hugagent, while keeping Tauri runtime files under Application Support. Existing desktop data is migrated safely, and legacy data is preserved when the destination already contains data.
• Quote both /workspace/... paths and already-expanded physical workspace paths before local Bash execution, so paths containing Application Support are not split and publish_site can find generated sites.
• Reduce the macOS titlebar height and remove duplicate brand/mini-rail top padding.
• Bump the desktop version to 0.2.4 and update desktop documentation and regression coverage.

Related issue / 关联 Issue

No public issue. This is a maintainer sync for a reproduced macOS desktop regression.

Type of change / 变更类型

• Documentation (document/**, README*.md)
• Example (examples/**)
• Repository metadata (Issue / PR templates, workflows)
• Other: maintainer CE runtime and desktop fix generated from the upstream full repository

Validation / 验证

• python scripts/build_ce.py --import-check --pytest-check --frontend-check
• npm --prefix src/frontend run build
• npm --prefix desktop run test:scripts — 16 passed
• cargo test --manifest-path desktop/src-tauri/Cargo.toml — 22 passed
• Targeted backend local-profile and process tests — 18 passed
• git diff --check

The generic root npm run preflight command is not available because the repository root has no package.json; the repository-native CE release checks above were used instead.

Checklist / 检查项

• I have read CONTRIBUTING.md.
• This change follows the maintainer CE derivation path for generated runtime files.
• Documentation links and command snippets touched by this change have been checked.
• No credentials, private endpoints, or internal deployment details are included.
• Bilingual public product documentation updated — not applicable; no document/zh-CN or document/en behavior page is changed.