CB-402 Increment 1: extract HerdrPeerLauncher abstract base

Behaviour-preserving refactor ahead of the second-adapter work. All herdr
transport shared by any peer kind — tab/pane placement, the CB-306
spawn-readiness gate, unique naming + CB-117 orphan reap, teardown, listing,
cwd resolution, and the peer-neutral git-forge grant — moves into a new
abstract HerdrPeerLauncher (Template-Method base). ClaudeCodeLauncher becomes
a final subclass supplying only the two Claude-specific seams: the `claude`
name prefix and buildLaunch(), which encodes the subscription boundary
(ANTHROPIC_BASE_URL + SubscriptionGuard assert, inline --mcp-config and
--append-system-prompt reply charter).

The base owns the injectable clock + sleeper for the readiness gate; the poll
interval is baked into the sleeper, so the vestigial spawnReadyPollMs field is
dropped from the base and from the full testability constructor (the explicit
sleeper already encodes it). The 6-arg and 8-arg production constructors keep
their signatures; three full-ctor test sites drop the now-unused poll argument.

No behaviour change: 242 tests green, both refactored files 0 IDE problems.

bridged/src/test/java/dev/ltms/bridged/session/SessionManagerTest.java

@@ -350,7 +350,7 @@ class SessionManagerTest {
         ClaudeCodeLauncher workers = new ClaudeCodeLauncher(
                 new AgentControl(herdr), new WorkspaceControl(herdr),
                 new SubscriptionGuard(Set.of("gx00.gw")), Map.of(cfg.profile(), cfg), cfg.profile(), _ -> null,
-                1, 1, () -> clock[0], () -> clock[0] += 10);
+                1, () -> clock[0], () -> clock[0] += 10);
         SessionManager sessions = new SessionManager(workers, new GitWorktrees(), () -> 0L, 0);
 
         assertThrows(PeerUnreachableException.class,

bridged/src/test/java/dev/ltms/bridged/worker/ClaudeCodeLauncherTest.java

@@ -350,7 +350,7 @@ class ClaudeCodeLauncherTest {
                 new AgentControl(herdr), new WorkspaceControl(herdr),
                 new SubscriptionGuard(Set.of("gx00.gw")),
                 workerConfigMap("ltms-local", null), "ltms-local", _ -> null,
-                5000, 300, () -> clock[0], sleeper);
+                5000, () -> clock[0], sleeper);
 
         PeerHandle handle = svc.spawn(new SpawnRequest(null, null, null));
 
@@ -370,7 +370,7 @@ class ClaudeCodeLauncherTest {
                 new AgentControl(herdr), new WorkspaceControl(herdr),
                 new SubscriptionGuard(Set.of("gx00.gw")),
                 workerConfigMap("ltms-local", null), "ltms-local", _ -> null,
-                1000, 50, () -> clock[0], () -> clock[0] += 50);
+                1000, () -> clock[0], () -> clock[0] += 50);
 
         PeerUnreachableException ex = assertThrows(
                 PeerUnreachableException.class,
@@ -409,7 +409,7 @@ class ClaudeCodeLauncherTest {
                 new AgentControl(herdr), new WorkspaceControl(herdr),
                 new SubscriptionGuard(Set.of("gx00.gw")),
                 workerConfigMap("ltms-local", null), "ltms-local", _ -> null,
-                0, 300, () -> clock[0], () -> clock[0] += 1);
+                0, () -> clock[0], () -> clock[0] += 1);
 
         PeerHandle handle = svc.spawn(new SpawnRequest(null, null, null));