v0.6.5 - rebased on plx-native v0.6.5, Jellyfin 12 authentication

First release of Butaca as its own repository, and the first built on plx-native's v0.6.5 line.

What's in it

Rebased onto upstream plx-native v0.6.5. The whole 0.6 line came across: the decoder
race fix that stopped crashes at the start of playback, failure screens that name your
television and the reason, opt-in crash/usage reporting with its consent flow, and IPv6
redaction in event logs. BACK at Home now hands the screen to the TV's launcher, the way
webOS 5.x itself behaves, instead of asking "Exit?".

Jellyfin 12 authentication. Jellyfin 12 servers removed the legacy X-Emby-* headers
the client used, which broke sign-in against updated servers even with correct credentials.
The client now authenticates over the standard Authorization: MediaBrowser header -
accepted by 10.x and 12 alike - while media, stream and image URLs keep the api_key
parameter both versions honour. Verified against a live Jellyfin 12.0.0 server, and on a
webOS 5.5 television: sign-in from a seeded config, Home with shelves, playback.

The project's own identity and history. Butaca lives in this repository as a git fork
now: the full history of the port, the merge of upstream v0.6.5 and every fix is public
and bisectable. Screenshots in the README come from the desktop simulator build running
against a real server.

Not in it yet

There is no installable package in this release. First-run onboarding and the stable
package are tracked in #2; translations in #1, our own error-report collection in #3 and
the new icon set in #4.

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En español

Primera release de Butaca como repositorio propio y la primera sobre la línea v0.6.5 de
plx-native. El rebase trae todo el 0.6 de upstream (fix de la carrera del decodificador,
pantallas de fallo con diagnóstico, reportes opt-in con su consentimiento, redacción de
IPv6 en logs). Se arregla el inicio de sesión contra servidores Jellyfin 12 (que
eliminaron las cabeceras X-Emby-*): el cliente autentica ahora con la cabecera estándar
Authorization: MediaBrowser, compatible con 10.x y 12, verificada contra un servidor real
y en una TV webOS 5.5. El proyecto pasa a ser un fork git público con toda su historia. No
hay paquete instalable todavía: el onboarding y el paquete estable llegan con el issue #2
(primer arranque para nuevos usuarios), junto a #1 (traducciones), #3 (recogida propia de
informes de error) y #4 (nuevo icono).