feat: phase 2 quick wins (#65 #69 #72)

- #65: update policies + per-agent version pinning
  - add settings.update_policy (stable/latest/skip)
  - add AgentDef.pin_version
  - honor both in update_cmd
  - add update_policy tests

- #69: REPL color theme CLI command
  - add am theme [name] (show/switch)
  - persist selected theme to config

- #72: doctor checks local model runtimes
  - verify ollama and llama-server on PATH
  - for ollama, also check server responds (ollama ls)

Version 0.4.4

src/doctor.rs

@@ -76,8 +76,7 @@ pub fn run(app: &App, runner: &dyn Runner) -> DoctorReport {
                 let empty = BTreeMap::new();
                 if let Ok(out) = runner.run(tool, &probe_args(tool), &empty, None, true) {
                     if out.code == 0 {
-                        let combined = format!("{}
-{}", out.stdout, out.stderr);
+                        let combined = format!("{}\n{}", out.stdout, out.stderr);
                         if let Some(v) = crate::version::find_version(&combined) {
                             detail = format!("{} (v{v})", path.display());
                         }
@@ -113,6 +112,45 @@ pub fn run(app: &App, runner: &dyn Runner) -> DoctorReport {
         }
     }
 
+    // --- local model runtimes (issue #72) -------------------------------
+    for runtime in ["ollama", "llama-server"] {
+        if let Some(path) = runner.which(runtime) {
+            let mut detail = path.display().to_string();
+            let empty = BTreeMap::new();
+            if let Ok(out) = runner.run(runtime, &["--version".to_string()], &empty, None, true) {
+                if out.code == 0 {
+                    let combined = format!("{}\n{}", out.stdout, out.stderr);
+                    if let Some(v) = crate::version::find_version(&combined) {
+                        detail = format!("{} (v{})", path.display(), v);
+                    }
+                }
+            }
+            // For ollama, also check that the server answers.
+            let status = if runtime == "ollama" {
+                match runner.run(runtime, &["ls".to_string()], &empty, None, true) {
+                    Ok(out) if out.code == 0 => Status::Ok,
+                    _ => {
+                        detail.push_str(" — server does not answer (ollama serve?)");
+                        Status::Warn
+                    }
+                }
+            } else {
+                Status::Ok
+            };
+            checks.push(Check {
+                name: runtime.to_string(),
+                status,
+                detail,
+            });
+        } else {
+            checks.push(Check {
+                name: runtime.to_string(),
+                status: Status::Ok,
+                detail: "not installed (optional)".to_string(),
+            });
+        }
+    }
+
     // --- configuration ---------------------------------------------------
     match &app.config_origin {
         Some(path) => checks.push(Check {