feat(v2): compose realtime monitor pipeline

docs/superpowers/plans/2026-07-22-t304-go-demo-delivery.md

@@ -208,7 +208,7 @@ git commit -m "feat(v2): add annotated evidence and alert dispatch"
 - Create: `v2/internal/monitor/monitor_test.go`
 - Modify: `v2/internal/spike/ort.go` only if an interface adapter is needed
 
-- [ ] **Step 1: Write failing orchestration tests using fakes**
+- [x] **Step 1: Write failing orchestration tests using fakes**
 
 ```go
 func TestMonitorPublishesLatestCompletedFrameAndOneAlert(t *testing.T) {
@@ -227,12 +227,12 @@ func TestMonitorDoesNotCreateFallEvidenceOnSourceFailure(t *testing.T) {
 }
 ```
 
-- [ ] **Step 2: Verify the monitor tests fail**
+- [x] **Step 2: Verify the monitor tests fail**
 
 Run: `Set-Location v2; go test ./internal/monitor -v`  
 Expected: FAIL because `internal/monitor` does not exist.
 
-- [ ] **Step 3: Implement the composition boundary**
+- [x] **Step 3: Implement the composition boundary**
 
 ```go
 type PoseRuntime interface { Run([]float32) ([]float32, error); Close() }
@@ -244,12 +244,12 @@ func (m *Monitor) Run(ctx context.Context) { /* source frame -> pose -> fall ->
 
 Create/open one ONNX Runtime instance before consuming frames and close it only when monitoring stops. Treat Pose/preprocess errors as non-fall status updates and continue/reconnect according to source state; do not terminate the Walk message loop. Only completed rendered frames enter the one-slot `Updates` channel, so a slow UI never queues stale video frames.
 
-- [ ] **Step 4: Run monitor, fall and full Go tests**
+- [x] **Step 4: Run monitor, fall and full Go tests**
 
 Run: `Set-Location v2; $env:CGO_ENABLED='1'; go test ./internal/monitor ./internal/fall ./...`  
 Expected: PASS.
 
-- [ ] **Step 5: Commit the monitor slice**
+- [x] **Step 5: Commit the monitor slice**
 
 ```powershell
 git add v2/internal/monitor v2/internal/spike/ort.go