feat(llm): the fallback chain's last link runs on our own hardware

`local:ornith-fleet:9b` joins opus -> haiku -> glm as the final link. Every
entry above it depends on somebody else's account staying funded and
unthrottled; this one depends on a GPU in the next room. It is last because it
is the weakest model, and present because a chain whose every link is external
is not a fallback chain, it is one outage in a trench coat.

Three small changes make it work:

- `build_provider_registry` accepts a provider with an empty `api_key_env`.
  A model on our own hardware has nothing to authenticate to, and the old
  behaviour SKIPPED a keyless provider — leaving the chain quietly one link
  shorter than it reads, which is the failure mode this whole area keeps
  producing.
- `provider_family` learns `ornith`/`ollama` for BARE names. A qualified
  `local:` spec was already answered by the split, but a bare one fell through
  to "unknown", and `cross_provider_judge` would then refuse a judge that is
  genuinely a different family from the Anthropic implementer.
- A test pins that the last link survives `resolve_provider`'s split-on-FIRST-
  colon: `local:ornith-fleet:9b` is provider `local`, model `ornith-fleet:9b`.
  Splitting on the last colon would ask for a provider named
  `local:ornith-fleet`, and the symptom would be a silent fall back to the
  default provider.

Infra: Ollama on tank and architect now binds 0.0.0.0 so the gateway (which has
no GPU) can reach it. `tailscale serve` cannot — Ollama rejects a non-local Host
header as a DNS-rebinding guard and OLLAMA_ORIGINS is CORS-only, so it 403s.
0.0.0.0 still includes loopback, so the microVM vsock pipe is unaffected;
verified on both nodes. This is an explicit trade: Ollama has no auth and its
API can pull and delete models, so it is now reachable from the LAN as well as
the tailnet. The drop-in carries the ufw one-liner to close the LAN side.

Co-Authored-By: Claude Opus 5 <[email protected]>

crates/cm-api/src/subscription.rs

@@ -132,9 +132,18 @@ fn is_transient(e: &cm_llm::LlmError) -> bool {
 /// default chain steps down within the subscription first, then leaves Anthropic
 /// entirely rather than making a capped window mean "the planner is gone".
 ///
+/// The last link runs on our OWN hardware. Every other entry — and every other
+/// link above it — depends on somebody else's account staying funded and
+/// unthrottled; `local:` depends on a GPU in the next room. It is last because
+/// it is the weakest model, and present because a chain whose every link is
+/// external is not a fallback chain, it is one outage in a trench coat.
+///
+/// Note the model half contains a colon (`ornith-fleet:9b`), which is why
+/// `resolve_provider` splits on the FIRST one only.
+///
 /// Override with `CLAWMATES_MODEL_FALLBACK` (comma-separated). An empty value
 /// disables fallback and restores plain "503 and wait".
-const DEFAULT_FALLBACK: &str = "claude-haiku-4-5-20251001,glm:glm-4.7";
+const DEFAULT_FALLBACK: &str = "claude-haiku-4-5-20251001,glm:glm-4.7,local:ornith-fleet:9b";
 
 /// The chain to walk after `requested`, with `requested` itself removed so a
 /// capped model is never retried as its own fallback.
@@ -396,7 +405,22 @@ mod tests {
     fn the_chain_excludes_the_model_that_just_failed() {
         // No env override in scope: this asserts the SHIPPED default.
         let chain = fallback_chain("claude-opus-4-8");
-        assert_eq!(chain, vec!["claude-haiku-4-5-20251001", "glm:glm-4.7"]);
+        assert_eq!(
+            chain,
+            vec![
+                "claude-haiku-4-5-20251001",
+                "glm:glm-4.7",
+                "local:ornith-fleet:9b"
+            ]
+        );
+        // The last link must survive `resolve_provider`'s split, which takes the
+        // FIRST colon only — `local:ornith-fleet:9b` is provider `local`, model
+        // `ornith-fleet:9b`, and a split on the last colon would ask for a
+        // provider named `local:ornith-fleet`.
+        let last = chain.last().unwrap();
+        let (provider, model) = last.split_once(':').expect("a provider-qualified spec");
+        assert_eq!(provider, "local");
+        assert_eq!(model, "ornith-fleet:9b");
         assert!(!fallback_chain("claude-haiku-4-5-20251001")
             .iter()
             .any(|m| m == "claude-haiku-4-5-20251001"));