Remove opencode package + vm acp command (dead code)

The `internal/opencode` package and the `opencodeCapability` that
consumed it were hard-wired to wait for opencode on guest port 4096
when an image shipped an initrd. After the prune commits (void /
alpine / customize.sh / image build all removed), nothing banger
produces today carries an initrd, so the capability's wait path was
unreachable: every startup short-circuited to the "direct-boot, skip
opencode" branch.

Same logic for `banger vm acp`: it SSHes to `opencode acp --cwd
<path>`, a binary the golden image no longer ships. Users who run
their own image with opencode can still invoke
`ssh vm -- opencode acp --cwd /root/repo` directly — no banger
scaffolding required.

Removed:
- internal/opencode/ (whole package, 255 LOC incl. tests)
- internal/daemon/opencode.go (opencodeCapability)
- cli `vm acp` command + its helpers (runVMACP, sshACPCommandArgs,
  vmACPRemoteCommand) + their tests
- The opencodeCapability{} entry in registeredCapabilities() plus
  the test that pinned its presence
- `wait_opencode` progress-stage label from the vm-create renderer
- Stale mentions in daemon/doc.go, README, and webui test fixtures

~480 lines gone, 12 added. `banger/internal` is now 25 packages
instead of 26.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/daemon/capabilities.go

@@ -56,7 +56,6 @@ func (d *Daemon) registeredCapabilities() []vmCapability {
 	}
 	return []vmCapability{
 		workDiskCapability{},
-		opencodeCapability{},
 		dnsCapability{},
 		natCapability{},
 	}

internal/daemon/capabilities_test.go

@@ -144,13 +144,13 @@ func TestContributeHooksPopulateGuestAndMachineConfig(t *testing.T) {
 	}
 }
 
-func TestRegisteredCapabilitiesIncludeOpencode(t *testing.T) {
+func TestRegisteredCapabilitiesInOrder(t *testing.T) {
 	d := &Daemon{}
 	var names []string
 	for _, capability := range d.registeredCapabilities() {
 		names = append(names, capability.Name())
 	}
-	want := []string{"work-disk", "opencode", "dns", "nat"}
+	want := []string{"work-disk", "dns", "nat"}
 	if !reflect.DeepEqual(names, want) {
 		t.Fatalf("capabilities = %v, want %v", names, want)
 	}

internal/daemon/doc.go

@@ -58,7 +58,6 @@
 //	session_controller.go  guestSessionController, sessionRegistry
 //	ssh_client_config.go   daemon-managed SSH client key material
 //	workspace.go           ExportVMWorkspace, PrepareVMWorkspace
-//	opencode.go            opencode host-side helpers
 //
 // Host bootstrap (in this package):
 //

internal/daemon/opencode.go

@@ -1,25 +0,0 @@
-package daemon
-
-import (
-	"context"
-	"strings"
-
-	"banger/internal/model"
-	"banger/internal/opencode"
-)
-
-type opencodeCapability struct{}
-
-func (opencodeCapability) Name() string { return "opencode" }
-
-func (opencodeCapability) PostStart(ctx context.Context, d *Daemon, vm model.VMRecord, image model.Image) error {
-	if strings.TrimSpace(image.InitrdPath) == "" {
-		// Direct-boot images (OCI pulls) don't ship the opencode
-		// service — skip the readiness check so the VM isn't marked
-		// as error for lacking an opinionated add-on.
-		return nil
-	}
-	return opencode.WaitReady(ctx, d.logger, vm.Runtime.VSockPath, func(stage, detail string) {
-		vmCreateStage(ctx, stage, detail)
-	})
-}