feat(tags): add tagColor utility, TagPicker component, sidebar filter, list pills, header tag row

feat(db): persist tags field in conversations table

feat(db): migration v5 — add tags column to conversations

feat(types): add tags field to Conversation

docs: add conversation tags spec and implementation plan

fix: clipboard fallback, hover state, and scroll-on-switch bugs

fix: add missing LogViewer component and fix .gitignore

docs: add direct download link for v0.1.0 DMG

Initial release: LLMChat v0.1.0