* chore: ignore .worktrees directory
* feat: add tips banner below welcome panel on startup
- Fetch active/fallback tips from the configured CDN with a 3s timeout.
- Filter tips by semver, client version, and date range.
- Render the banner directly below the welcome panel on startup/resume.
- Support tag, multi-line text, subtext, automatic wrapping, and narrow-terminal safety.
* refactor(tui): use theme color methods in banner component
Replace raw chalk calls with currentTheme helpers: tag uses
boldFg('primary'), main text uses boldFg('textStrong'), and subtext
uses fg('textDim') without stacking the dim modifier on the already
dim shade. Strengthen tests to assert the exact themed ANSI output.
