v0.9.0 — Phase 1.5: Daily-Driver Update

New features:
• Auto-render markdown on GitHub, GitLab, and Bitbucket raw file URLs
• Local folder navigation — browse directories, click to render markdown files
• Tabbed sidebar — switch between Files and Outline (Table of Contents)
• "Render this page" button — render markdown on any page via popup
• Export/import settings as JSON (copy to/paste from clipboard)
• Named style profiles — save and switch between multiple setups
• Per-site style rules — auto-apply profiles based on URL patterns

Improvements:
• Document rendering mode redesigned with Word-like heading bands
• Anti-flicker CSS — no more raw text flash on page load
• ToC heading scroll offset — headings no longer hidden behind toolbar
• Consistent sidebar font sizing

New permissions:
• activeTab — for "Render this page" (temporary access on user click only)
• scripting — injects renderer into current tab (used with activeTab)