release: Floatick 0.3.3 — lightweight notes

[lucaslus]

Summary

• add a lightweight Notes workspace beside Todos
• support note search, pinning, archiving, autosave, Markdown preview, and shared tags
• unify Todo and Note title/content editing into one continuous document surface
• update the bilingual product website, changelog, README, architecture, testing, and release guidance
• prepare the 0.3.3+10 universal macOS candidate

Verification

• Release Candidate workflow passed formatting, analysis, full Flutter tests, universal release build, update-feed validation, architecture checks, and launch smoke test
• Astro production build passed
• English, Chinese, changelog, and 404 pages passed browser QA at 375px, 768px, and 1440px without runtime errors or horizontal overflow

Release

• accepted candidate tag: candidate/v0.3.3
• accepted candidate commit: a20a5a4eca9bc2de82c17c47a10ae83580c400d5
• merge strategy: merge commit (do not squash or rebase)