Resolves /api/* callers from session cookie first, Authorization
bearer second. Touches last_seen on success for future active-
sessions UI. Adds GetUserByID query used by the middleware.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Shared primitives for /api/* auth: mint a url-safe opaque token,
hash it for storage, verify a bcrypt password hash.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>