Remove the KVM tab: proxy, routes, config and state fields, UI

Not needed — the KVMs are reached over WireGuard.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

PLAN.md

@@ -417,39 +417,9 @@ something long in one, switch away and back, refresh — it's all still there.
   snapshot, the package is purged and the old cron line is gone, with the 515 snapshots it
   had taken left untouched and fully readable here — which is what adopting its naming
   bought. See `hamlet/docs/hosts.md`.
-- **KVM tab** — **shipped 2026-09-24** (`internal/api/kvm.go`, `KVM.tsx`, `config.KVM`).
-  Paste a device's address; its own web page appears in the tab. **Nothing in it knows
-  anything about any particular KVM** — the first device here is a Sipeed NanoKVM on `grid`
-  at `10.0.0.217`, but none of that is in the code.
-  **Why it proxies rather than framing the device directly.** Ham Lab is served over TLS and
-  a KVM usually is not, so a bare `http://…` iframe is blocked as mixed content before it
-  loads. Serving the device from Ham Lab's own origin (`/kvm/<id>/…`) fixes that, puts it
-  behind **Ham Lab's** login rather than a second one, and makes the iframe same-origin.
-  **The general problem, and the answer.** A device UI asks for its assets by absolute path
-  — `/assets/app.js`, `/api/whatever` — which no path prefix can rewrite away, and rewriting
-  bodies per device would not be general. So the prefix is only the entry point: any request
-  Ham Lab does not serve itself is routed to whichever KVM the asking page belongs to, read
-  from the **Referer**, falling back to a **cookie** when there is none (a WebSocket upgrade).
-  Ham Lab's own routes always match first, so a device can never shadow the console, and the
-  fallback is gated on a live session. The device never receives Ham Lab's session cookie,
-  and its `X-Frame-Options`/CSP/HSTS are dropped on the way out since Ham Lab is the origin
-  now. Redirects to the device's root are rewritten back through the prefix.
-  **One catch found in testing:** Ham Lab's own `frame-ancestors 'none'` forbids framing even
-  from the same origin, so `/kvm/` paths send `'self'` instead. Without that the iframe was
-  refused before it loaded.
-  **The keyboard** needs less than it sounds: a page cannot forward keys into an iframe and
-  does not need to, since one with focus receives them directly. Fullscreen plus
-  `navigator.keyboard.lock()` is what takes Escape, Tab and Ctrl-W back from the browser;
-  that is Chromium-only, and the tab says which version you are getting rather than
-  pretending.
-  **One KVM per machine, and the tab follows the machine switcher** (corrected the same day:
-  the first cut was a hub-side list you pointed at machines, which had it backwards). Switch
-  to `grid` and you get grid's; adding a second for a machine replaces the first. The
-  addresses are still kept **on the hub** rather than on each machine, because a KVM earns
-  its keep exactly when the machine is down and its own Ham Lab cannot answer — the hub
-  proxies the device either way — and a KVM need not belong to a machine Ham Lab manages at
-  all. Not done: holding the device's own login on the hub, so its page does not ask for a
-  second password.
+- **KVM tab** — shipped 2026-09-24, **removed 2026-11-09** at Mitchell's call: not needed —
+  the KVMs are reached over WireGuard (see `hamlet/docs/hosts.md`). It proxied a device's web
+  page through Ham Lab's origin; the code is in git history before that date.
 - **Skins** — 13 since 2026-09-19 (`themes.ts`: a palette is one `mk(…)` line): Dark,
   Light, Cyberpunk, Retro, **HUD** (hairlines of cyan on near-black, corner ticks, thin
   type), Nord, Gruvbox, Catppuccin + Latte, Dracula, Tokyo Night, Solarized Dark + Light;