The TV's sign-in screen tells the user to open …/device and enter the code,
but the approve page only worked when opened with ?code= (what the QR encodes)
— opening it bare showed 'Chybí kód zařízení v odkazu.' with no way to type
the code.
Add a code-entry field shown when the page is opened without ?code=: the user
types the XXXX-XXXX code from the TV, it's normalized (uppercase, dash/space
stripped, capped at 8) to the dash-less form the server stores before the /info
+ /approve lookups, then the sign-in form is revealed. Input formats live to
XXXX-XXXX; Enter submits; an unknown/expired code re-shows the field prefilled
for correction instead of dead-ending. The QR/direct-link path is unchanged
(CODE now also runs through the same normalizer, so a dashed link works too).
Docs: note the optional ?code= + normalization in device-auth-contract.md.
Verified: node syntax-check of the hook + inner page script, and 19 unit
assertions over the normCode/fmtCode/length-gate logic (dashed↔dashless,
formatting, cap, validation).
