Hourly polling added; search updates as you type

Added

• Scheduled hourly polling that automatically detects and fetches changed feed and GitHub sources, with per-source frequency control.
• fetch --changed to refresh only the sources where polling detected upstream changes.
• Per-source fetch buttons in the web status dashboard to trigger a fetch on demand.

Changed

• Smoother search: results now update as you type (debounced) with type-filter buttons for organizations, products, sources, and releases.

Fixed

• The search page no longer traps keyboard navigation.