claws: PATCH /api/claws/{id}/model — swap the runtime-bound model

Auto-provisioned agents (via the research + loops team wizard) show
up on the Agents page (same agents::insert → agents::roster path),
and PATCH /api/claws/{id} already handled name/job_title/system_prompt/
avatar/accent/wallpaper. The one thing that was NOT reachable from the
Agents page: swapping the model.

Add a dedicated endpoint:
- PATCH /api/claws/{id}/model { model: string }
- Persists via agents::set_model_binding (DB)
- Best-effort runtime rebind via RuntimeProvisioner::provision_claw
  (idempotent — overwrites agents.<alias>.model_provider on the
  shared ZeroClaw config)
- Audit-logged as 'agent.model_changed' with the new model in payload

Now an operator can open the Agents page, click a claw that was
auto-provisioned by the team wizard, and swap its model
(claude-sonnet-5 → glm-5.2 → whatever) without recreating the team.
Same DB row, same claw_id, same brain — just a new provider on the
next turn.

Frontend affordance not shipped in this commit — the endpoint is
usable via curl/psql/scripts today; a UI 'Model' picker on the claw
detail card can land in the next Agents-page pass.

crates/cm-api/src/routes/claws.rs

@@ -957,6 +957,61 @@ pub async fn patch(
     Ok(Json(updated))
 }
 
+#[derive(Deserialize)]
+pub struct SetModelRequest {
+    /// Model selector (claude / glm / glm-5.2 / kimi / gemini / groq /
+    /// specific model id like `claude-sonnet-5`). Resolved through the
+    /// same RuntimeProvisioner::provider_alias_for that team creation
+    /// uses, so shorthand + fully-qualified ids both work.
+    pub model: String,
+}
+
+/// `PATCH /api/claws/{id}/model` — swap the model bound to a claw
+/// (both the DB row + the live ZeroClaw runtime agent). Idempotent:
+/// re-runs safely if the runtime agent was previously deprovisioned.
+///
+/// This is the missing piece that lets an operator open the Agents
+/// page, click a claw that was auto-provisioned via the research or
+/// loops team wizard, and swap its model without going through the
+/// team-recreation flow. Complements `PATCH /api/claws/:id` (profile
+/// fields) which was already there.
+pub async fn set_model(
+    State(state): State<AppState>,
+    Authed(user): Authed,
+    Path(id): Path<AgentId>,
+    Json(body): Json<SetModelRequest>,
+) -> Result<Json<Agent>, ApiError> {
+    let agent = workspace_agent(&state, &user, id).await?;
+    let model = body.model.trim();
+    if model.is_empty() {
+        return Err(ApiError::BadRequest);
+    }
+    // 1. Persist the DB binding first — the runtime provision is
+    //    idempotent and non-critical for read-only Agents-page display.
+    cm_db::repo::agents::set_model_binding(&state.pool, id, model).await?;
+
+    // 2. Best-effort runtime rebind so live sessions pick up the new
+    //    model on their next turn. provision_claw overwrites
+    //    agents.<alias>.model_provider on the shared ZeroClaw config.
+    if let Some(provisioner) = crate::runtime_provision::RuntimeProvisioner::from_env() {
+        if let Err(e) = provisioner.provision_claw(id.as_uuid(), model).await {
+            eprintln!("set_model({id}): runtime rebind failed: {e}");
+        }
+    }
+
+    cm_db::repo::audit::append(
+        &state.pool,
+        user.workspace_id,
+        Actor::User(user.user_id),
+        "agent.model_changed",
+        "agent",
+        &id.to_string(),
+        json!({ "model": model }),
+    )
+    .await?;
+    Ok(Json(agent))
+}
+
 /// DELETE /api/claws/{id} — destructive (§7.7): workspace owners or the
 /// claw's manager only. Soft delete keeps rows for audit.
 pub async fn delete(