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

tests/doctor_test.rs

@@ -11,7 +11,7 @@ fn report_contains_core_checks() {
     let runner = SystemRunner::new(false, false, &app.log);
     let report = doctor::run(&app, &runner);
     let names: Vec<&str> = report.checks.iter().map(|c| c.name.as_str()).collect();
-    for expected in ["git", "config", "config-schema", "state", "install-dir", "bin-on-path"] {
+    for expected in ["git", "config", "config-schema", "state", "install-dir", "bin-on-path", "ollama", "llama-server"] {
         assert!(
             names.contains(&expected),
             "missing check '{expected}' in {names:?}"

tests/update_policy_test.rs

@@ -0,0 +1,67 @@
+use agent_manager::commands::update_cmd;
+use agent_manager::config::UpdatePolicy;
+use agent_manager::state::{InstalledEntry, StateFile};
+use std::collections::BTreeMap;
+
+mod common;
+
+fn installed_state(name: &str, version: &str) -> StateFile {
+    StateFile {
+        version: 3,
+        installed: BTreeMap::from([(
+            name.to_string(),
+            InstalledEntry {
+                name: name.to_string(),
+                version: Some(version.to_string()),
+                method: "binary".to_string(),
+                install_dir: "/tmp".to_string(),
+                bins: vec![name.to_string()],
+                run: name.to_string(),
+                installed_at: "2026-01-01T00:00:00Z".to_string(),
+                updated_at: None,
+                pid: None,
+                started_at: None,
+            },
+        )]),
+        sessions_count: 0,
+        last_used: None,
+        annotations: BTreeMap::new(),
+    }
+}
+
+fn agent_yaml(name: &str, pin: Option<&str>) -> String {
+    let pin_line = pin
+        .map(|v| format!("    pin_version: \"{v}\"\n"))
+        .unwrap_or_default();
+    format!(
+        "agents:\n  - name: {name}\n    display_name: {name}\n    run: \"{name}\"\n    install:\n      type: binary\n      binary: {name}\n{pin_line}"
+    )
+}
+
+#[test]
+fn update_policy_none_blocks_all() {
+    let body = agent_yaml("pi", None);
+    let mut app = common::test_app("policy_none", &["--yes"]);
+    app.config.settings.update_policy = Some(UpdatePolicy::None);
+    app.state.save(&installed_state("pi", "0.1.0")).unwrap();
+    let code = update_cmd::run(&app, None, true).unwrap();
+    assert_eq!(code, 0);
+}
+
+#[test]
+fn pinned_agent_is_skipped() {
+    let body = agent_yaml("pi", Some("0.1.0"));
+    let app = common::test_app("pinned_ok", &[]);
+    app.state.save(&installed_state("pi", "0.1.0")).unwrap();
+    let code = update_cmd::run(&app, Some("pi"), false).unwrap();
+    assert_eq!(code, 0);
+}
+
+#[test]
+fn pinned_agent_mismatch_warns() {
+    let body = agent_yaml("pi", Some("0.1.0"));
+    let app = common::test_app("pinned_warn", &[]);
+    app.state.save(&installed_state("pi", "0.2.0")).unwrap();
+    let code = update_cmd::run(&app, Some("pi"), false).unwrap();
+    assert_eq!(code, 0);
+}