M6 stub. Validates seed_track param (400 on missing/blank/bad UUID),
looks up the track (404 on miss), returns RadioResponse with a single
TrackRef. M4 will replace the body with similarity-driven candidate
pool + scoring; the request/response shape is final.
Returns the authenticated user (id/username/is_admin). Shape
matches UserView used in the login response so SPA stores stay
typed against one interface.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Deletes the session row keyed by the cookie/bearer token and
clears the cookie on the client. Best-effort DB delete — logout
still succeeds for the client if the row's already gone.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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