Intent Guard v1.0.0: first release

Added

• Focus sessions: type what you're working on in the popup and pick how long you can drift (1, 2, 5 or 10 minutes) before a nudge.
• Every page you view during a session is judged against the task on a four-level scale (distraction, loosely related, useful, exactly the task), summing each side with a 60% threshold.
• Unclear pages neither start nor stop the drift clock.
• A calm corner nudge with Back to task (last on-task page), It's part of it (allow the site for the session) and 5 more minutes.
• Re-checks on tab switches and single-page-app navigation; sends only origin and path, title and up to 800 characters of text.
• One request at a time, cached per task and page; errors and rate limits never show on the page.
• Popup with session status and an API key check on save.