feat(appgate): apps with their own login can skip the node login

Some apps carry a complete account system and are broken by an upstream
challenge: git clients speak basic-auth (not browser cookies), and a
BTCPay checkout link handed to a customer must open for that customer.
Both were behind the gate's login page — the "non-browser clients need an
access token" gap disclosed in five consecutive releases.

- New manifest port policy `auth: open`: the daemon still fronts the port
  exactly like `gated` (loopback pin, external binds, frame-header fixes,
  app-down retry page, Tor upstream) but serves it without the login
  challenge. Requires auth_rationale, same burden of proof as `none`.
  Gitea 3001 and BTCPay 23000 declare it.
- Runtime operator override per app (security.set-app-gate → app-configs/
  <id>.json "gateEnabled"), surfaced as Settings → app → Access control.
  Wins over the manifest in both directions and applies on the next
  request — no restart, and it works today on catalog-covered apps whose
  signed manifest still says `gated`.
- The gate resolves policy per-request from the live port map, so a
  toggle takes effect without waiting for the 60s rebind sweep. "Off"
  never releases the port: gated apps are loopback-pinned, so releasing
  would strand them, not open them.
- security.app-gate-status now reports gate_enabled + any override.
- New guard test pins the `auth: open` set (both entries reviewed); the
  `auth: none` count moves 25 → 26, absorbing pre-existing drift from the
  phoenixd onboarding (loopback JSON API with its own generated password).
- Docs: the manifest spec's ports row documented only host/container/
  protocol — bind, auth, auth_rationale and session_passthrough were
  undocumented. Added a full "Ports & the app gate" section plus a
  developer-guide entry telling app authors to enforce their own auth
  regardless, since the operator can flip the gate either way.

Verified live on archi-dev-box from an external address: gated → 401 gate
page; override off → Gitea 200 own page, BTCPay 302 to its own login,
git-over-HTTP info/refs 200; override on → 401 again; clear → default.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## v1.8.4-alpha (draft — date set at cut)
 
+- **Apps with their own login can now skip the node's login screen — Gitea and BTCPay Server do so out of the box.** Some apps bring a complete account system of their own, and putting the node's password page in front of them broke real workflows: git clients can't answer a browser login, and a BTCPay checkout link handed to a customer must open for that customer. These apps are now served directly on their own login, while the node still fronts the connection for everything else it does (embedding fixes, the "app is restarting" page, Tor). Every app gets a new **Settings → app → Access control** switch, so you can put the node login back in front of any app — or take it away from one — with one click, effective immediately. App developers declare the default in their manifest (`auth: open`), documented in the developer guide.
+
 - **The phone remote now works inside apps on the TV — tap, scroll, and type everywhere.** The companion remote and keyboard drove the dashboard beautifully but died at the edge of any app screen (Gitea, BTCPay, and friends): for the browser, each app is a separate website embedded in the page, and simulated input is forbidden from crossing that wall. The on-screen display now accepts the remote's input the way a real mouse and keyboard arrive — below the page, through the browser itself — so it lands anywhere on screen, app screens and tabs included. Taps click, two-finger scrolling scrolls the app, and typing goes into whichever field you tapped. Existing kiosks pick this up with the update, no reinstall needed.
 - **While you're driving with the phone remote, the old mouse pointer gets out of the way.** The computer's own pointer used to sit frozen wherever the physical mouse last left it — a second, dead cursor next to the live orange one. It now hides while the remote is in use and returns half a minute after the last remote input.
 - **"Are you sure?" questions no longer freeze the remote.** A handful of confirmations (clearing mesh history, rebooting, deleting a backup, uninstalling an app) used the browser's built-in popup, which stops the whole page — including remote input — until someone clicks it with a real mouse. From the couch, that meant asking a question you couldn't answer. All of them are now proper in-app windows in the house style, fully driveable by remote.