Release v0.3.0 with bilingual providers and offline study

[Ldsystem]

Summary

• add live English and Simplified Chinese UI, tray, settings, study, and error copy
• add explicit Google Cloud, Baidu VIP, and Microsoft Translator routing with provider-scoped Keychain credentials
• bundle a compact offline English to Simplified Chinese starter textbook
• keep selection translation non-activating while silently updating the personal wordbook
• update bilingual documentation and audit compact self-contained universal packaging
• prepare application version 0.3.0

Verification

• pnpm check: 21 files, 128 tests
• Rust: strict Clippy; 133 passed, 7 manual ignored
• independent review accepted exact head c22978c
• universal macOS build: arm64 plus x86_64
• signed bundle audit: 20,788 KiB app, no sidecars, no duplicate external textbook
• DMG: 9,511,629 bytes

Platform qualification

macOS is qualified. Windows adapters remain unqualified because this macOS host does not provide the Windows SDK.

[Ldsystem]

Release gate note: Frontend and macOS core are green, and independent review accepted exact head c22978c. The advisory Windows compile check reproduces the pre-existing failure already present on origin/main and PR #2 (missing apply_non_activating_tool_window plus windows crate API/type drift). This release remains explicitly macOS-only; Windows is not claimed as qualified.