Replace com.sun.net.httpserver routing with Thorium's Server/Action/annotation
pattern. TaskController now owns @Get/@Post routes, form binding via data-mapping,
and the renderPage()/esc() helpers moved from Main. Main reduced to a 9-line
Thorium server entry point.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Tasks are now stored in SQLite (DB_PATH env var, defaults to ./tasks.db).
Pre-seeding runs only when the table is empty, so upgrades preserve data.
This is the v1.0.0 baseline for the persistence demo.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>