Adds RawAutocomplete<EmailAddress> to the To and Cc fields in the compose screen. As the user types (minimum 2 chars), suggestions are fetched from the local DB by searching from/to/cc columns of cached emails. Selecting a suggestion appends it to any existing addresses already in the field (comma-separated). New repository method searchAddresses() returns deduplicated EmailAddress objects matching the query string. Closes #11 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>