Providers and hosts: what runs, and where, as independent choices

A session now names a provider (what: driver kind, command, models) and
optionally a host (where: an ssh target). Keeping them independent is
what the real setup needs -- the backend runs where the phone can reach
it, which isn't where the CLI is installed -- and it means any provider
can be sent to any host rather than a machine being baked into one.

The first provider is claude-cli, named for the CLI rather than bare
"claude", which would suggest the credit-billed API. A fresh config is
seeded with it so a new install has something to spawn and a worked
example to edit; echo stays a built-in provider needing no config.

ssh.rs builds the child process either way: locally, or `ssh -T` with
BatchMode and keepalives, every argument single-quoted for the remote
shell (a working directory that tries to close the quote and start a
command is covered by a test), and `exec` so dropping the connection
takes the CLI down instead of orphaning it.

App: the spawn screen reads /providers and /hosts instead of hardcoded
lists, so config changes need no rebuild. Chip rows are FlowRow, fixing
the reported bug where a row of models that didn't fit wrapped *inside*
each chip -- one letter of "haiku" per line -- rather than onto a second
line.

Verified: 29 tests, clippy clean; the same claude-cli provider run once
locally and once over ssh, with the remote one visibly in a different
environment; an unknown host name refused with the configured list; and
the spawn screen on the emulator showing server-driven providers, hosts,
and models that wrap.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017xn8nHw1tw1R6PtiY1eEtw

AGENTS.md

@@ -101,6 +101,15 @@ Established 2026-08-25, and it decides more than it looks like:
   network namespaces inside one machine and drives the server through it
   — a genuine handshake against 10.66.0.1 with pinned TLS, no router or
   phone involved. That's the way to verify the wg0-only posture.
+- **The `claude` CLI is installed in this VM only, not on the host.** So
+  the backend reaches it the same way it would any other machine: a
+  configured host, and a session that names it. For the host to ssh in,
+  the VM needs an inbound port forward in its launch configuration
+  (qemu `hostfwd`) — usermode networking has none by default.
+- **`config.json` is shared with the host too**, so it is the *production*
+  config: don't leave test tokens or throwaway hosts in it. Point
+  development at a scratch one instead:
+  `--config /tmp/…/config.json --data-dir /tmp/…/sessions --port 8444`.
 
 ## Things that have bitten