A guest login: temporary, look-only, revocable

Users -> Guest logins makes a throwaway user name and password, good for half
an hour by default, to hand to somebody who wants to see the console. It is a
normal account with `guest: true` and an expiry, so login, sessions and the
saved look need no special case, and it is left out of the account list, out of
"the last account can't be removed", and out of the one account an empty user
name means.

What a guest may do is one allow-list, checked in the auth middleware, rather
than a flag ~190 handlers have to remember. The list is matched by asking the
router which handler a request would reach, so it cannot drift from the routes
it names, and it is checked against the scoped path — /api/nodes/grid/procs is
/api/procs on grid — because the hub proxies to a node with a token that is
full control of that node. The node cannot tell a guest from its owner, so the
only place it can be stopped is here, before the request leaves.

A guest gets the dashboard, containers, stacks, disks, hardware, ZFS and usage,
on this machine and on any managed one, and nothing else: no terminal (attaching
is a GET, and it is a root shell), no files, no container logs or environments,
no stack files, no alert channels, no cron, no tokens, no settings, no power.

Expiry is enforced on every request and swept once a minute, so a console left
open on a visitor's phone stops within the minute rather than at their next
click; revoking signs them out at once. The console hides what a guest cannot
use and says how long is left where the power button would be.

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

PLAN.md

@@ -18,6 +18,7 @@ stub tab or a roadmap item.
 | Data | `/home/core/apps/hamlab/` — `config.yaml`, `state.db` (SQLite) | `apps/` is the nightly rsync target to `grid`, so it's backed up for free. |
 | Ingress | NPM proxy host `hamlab.bigham.dev` → `:8100`, LE cert, WebSockets on, caching off, force-SSL + HSTS + HTTP/2 set in a **second** API call (NPM drops them on create-with-new-cert) | `*.bigham.dev` already resolves; the proxy host alone makes it live. |
 | Repo | Gitea `mitchell/hamlab`, private, `main` | Created 2026-09-17. |
+| Guest logins | A **guest** is an account like any other, with `guest: true` and an expiry, so login, sessions and prefs need no special case. What it may *do* is one allow-list of routes checked in the auth middleware, not a flag each handler honours. Denied by default. | Built 2026-09-27, asked for the same day. There are ~190 routes; a per-handler check would be wrong the first time a route was added. The list is matched by asking the router which handler a request would reach, so it cannot drift from the routes it is about, and it is applied to the *scoped* path (`/api/nodes/grid/files/read` → `/api/files/read`) because the hub proxies to a node with a token that is full control of it — the node cannot tell a guest from its owner, so the decision has to be made on the hub. |
 | Machines | **A view shows one machine: the one in the switcher.** No hub-side page lists or aggregates what its nodes are doing. To see or change anything on another machine, switch to it. | Mitchell, 2026-09-25, cutting a fleet-wide updates list out of the Docker tab. The switcher is the only place a machine is chosen, so there is exactly one answer to "which machine am I looking at" — a page that quietly reaches across breaks that, and it is never obvious which machine an action would land on. The hub still *proxies* for a node, and hub-only admin (Machines, Users, Settings, Alerts) is unaffected. |
 
 ## Layout