Merge CB-538: opencode peers launch with --auto

A spawned peer has no human at its pane, so an approval prompt is not a pause —
it is a wedge. The agent stops, looks identical to a legitimate mid-turn wait,
and can never reach its bridge_reply, so the delegation dies silently and the
lead learns nothing until the timeout.

Unconditional rather than a per-profile knob, which is the right call: there is
no configuration under which a bridge-spawned opencode worker WANTS to block on
an approval it has no way to answer. opencode's help calls --auto 'dangerous!',
and that warning is written for a human at a terminal; the blast radius here is
already bounded by the layer above — a worker runs in its own git worktree, on
its own branch, off-subscription, and cannot merge. The lead is the gate.

Reviewed by me rather than fanned out: 24 lines across one method and its two
tests, below the threshold where a reviewer pass pays for itself.

argvWithModel is re-signatured to take composed argv instead of building it,
so the two flag-appenders compose rather than each owning construction.

bridged/src/main/java/dev/ltms/bridged/worker/OpenCodeLauncher.java

@@ -144,7 +144,7 @@ public final class OpenCodeLauncher extends HerdrPeerLauncher {
             workerEnv.put("OPENCODE_CONFIG", writeConfig(cfg).toString());
         }
         applyGitToken(workerEnv, cfg);
-        return new Launch(workerEnv, argvWithModel(cfg));
+        return new Launch(workerEnv, argvWithModel(argvWithAuto(cfg), cfg));
     }
 
     /**
@@ -161,9 +161,24 @@ public final class OpenCodeLauncher extends HerdrPeerLauncher {
         return cfg.baseUrl() != null && !cfg.baseUrl().isBlank();
     }
 
-    /** The launch argv plus, when a model is configured, the opencode {@code -m provider/model} flag. */
-    private List<String> argvWithModel(BridgedConfig.Worker cfg) {
+    /**
+     * The launch argv plus the unconditional {@code --auto} flag, which auto-approves the
+     * permissions opencode does not explicitly deny. It is unconditional, not a preference: a
+     * spawned peer has no human at its pane — the bridge spawned it — so one that stops at an
+     * approval prompt is a wedged agent, indistinguishable from a legitimate mid-turn wait and
+     * unable to end its turn with {@code bridge_reply}. opencode's own help calls this
+     * "dangerous!", but the blast radius here is already bounded by design: a worker runs in its
+     * own git worktree on its own branch, is off-subscription, and cannot merge — the lead is the
+     * gate.
+     */
+    private List<String> argvWithAuto(BridgedConfig.Worker cfg) {
         List<String> argv = mutableArgv(cfg.argv());
+        argv.add("--auto");
+        return argv;
+    }
+
+    /** The launch argv plus, when a model is configured, the opencode {@code -m provider/model} flag. */
+    private List<String> argvWithModel(List<String> argv, BridgedConfig.Worker cfg) {
         if (cfg.model() != null && !cfg.model().isBlank()) {
             argv.add("-m");
             argv.add(cfg.model());