replace SSHPublicKeyStr field on Model with a closure-based authCmd that
fires, the public key lives only in the goroutine stack not on the
long-lived Model struct
Prevents key material exposure in heap dumps if the process crashed
previously main.go handled auth directly, it connected to the database,
ran migrations, created a JWT manager and SSHAuthService, and
authenticated the SSH key before the TUI even started. this commit rips
all of that out
Auth now happens inside the TUI during the splash screen via
splashAuthCmd, which calls the /auth/token endpoint. if no user exists
or the fingerprint it auto-creates one using the SSH public ke, so there
is no longer a separate registartion flow. The token and user com back
in the response.
once authed splashViewInitCmd fires a single /view/init request that
loads everything needed to start the app, products, cart, addresses,
cards, and orders, before switching to the shop page
on the model side, User/*models.user and gossh.PublicKey were replaced
with plain Fingerprint and SSHPublicKeyStr strings, and NewModelWithAuth
was updated too
