v0.4.5: VMware UEFI fix, static musl binary, Forms auth + SSO config

VMware UEFI / Casper boot fix:
- Linux cmdline for Debian/Ubuntu/Mint/Pop!_OS/elementary now uses the
  canonical Casper `iso-url=` option and `ds=nocloud`, matching the
  fix Bootimus shipped in v0.1.67. The previous
  `boot=casper netboot=url url=… ip=dhcp ---` form booted fine on
  bare-metal UEFI but hung at "cloud-init running" on VMware guests
  because subiquity / cloud-init can't reach a metadata datasource
  through PXE.

Static binary (matches Bootimus v0.1.70):
- Dockerfile build stage now compiles against
  x86_64-unknown-linux-musl. The resulting /openpxe has no glibc
  dependency at all; the runtime stage still ships Debian slim for the
  samba/wimtools/nfs-common shellouts, but a future scratch/distroless
  variant is now a one-line swap. Cuts a class of "GLIBC_2.39 not
  found" surprises on older RHEL/Rocky hosts.

Forms auth (Sonarr/Radarr-style):
- New AdminStore in openpxe-core: single admin record persisted to
  <work_dir>/auth.json, bcrypt-hashed credentials, rotation requires
  current password.
- New SessionStore in openpxe-http-api: in-memory UUID-keyed sessions
  with 24h sliding TTL, openpxe_session HttpOnly cookie.
- Endpoints: POST /api/setup (first-run), POST /api/login, POST
  /api/logout, GET /api/me, PUT /api/me/credentials (rotates and
  revokes every other session).
- Auth middleware gates /api/* once the admin is configured;
  passes through entirely until then (tests + fresh installs ride this
  path). Allowlists PXE-essential paths (/boot.ipxe, /iso/*, /ipxe/*,
  /api/queue/join, /api/queue/poll/*) so iPXE clients still work
  without a cookie they can't send.
- WebUI: first-run setup card, login card, logout chip in the sidebar
  footer, Account card in Settings for rotating creds. Auth screen is
  fully styled (centered narrow card, matches Sonarr layout).

SSO config (FleetDM-shaped, storage-only):
- New SsoStore in openpxe-core: { enabled, idp_name, metadata,
  metadata_url } persisted to <work_dir>/sso.json with size caps and
  URL-scheme validation.
- Endpoints: GET /api/sso, PUT /api/sso. Validation: enabling SSO
  without either metadata or metadata_url returns 400.
- WebUI: SSO card in Settings with a URL-vs-XML mode switch and an
  inert "Sign in with X" button on the login screen while runtime
  flow is pending. Per the brief: no Entity ID field (defaults to the
  advertised public_base_url internally when SAML wiring lands).

Quality:
- 132 tests passing (was 106 in v0.4.4): +5 auth unit tests, +5 SSO
  unit tests, +7 auth integration tests, +1 SSO integration test, +1
  regression guard pinning the new Casper cmdline.
- cargo clippy --workspace --all-targets clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

crates/http-api/Cargo.toml

@@ -32,6 +32,8 @@ futures.workspace = true
 mime.workspace = true
 mime_guess.workspace = true
 uuid.workspace = true
+# v0.4.5 Forms auth: lock-free session store and cookie helpers.
+parking_lot.workspace = true
 
 [dev-dependencies]
 tokio = { workspace = true, features = ["macros", "rt", "rt-multi-thread", "time"] }