Verifies bcrypt password hash, mints a session token, stores its
sha256 in the sessions table, and returns the token in both the
response body (for Flutter) and an httpOnly/SameSite=Strict
cookie (for the web SPA).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Introduces internal/api with Mount(), the {error:{code,message}}
response shape, and stubbed login/logout/me so later tasks can
land one handler at a time without breaking the build.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
bvandeusen