fix(cog-pose-estimation): emit frames under default config (ADR-159 A1)

pose_v1 has no confidence head, so infer() emits a constant 0.185 per
frame. The config default_min_confidence was 0.3 and the runtime gates
on confidence >= min_confidence, so a default install silently emitted
ZERO pose.frame events while health reported healthy.

- Add inference::MODEL_TYPICAL_CONFIDENCE (0.185, the validation PCK@50)
  as the single published per-frame confidence.
- Pin default_min_confidence() to MODEL_TYPICAL_CONFIDENCE so a default
  install clears its own gate and emits.
- Warn at run.started when min_confidence exceeds the model typical
  confidence (disclosed, not silent); document the trade-off in the
  config field, the JSON schema, and inference.rs.

Failing-on-old test: default_config_emits_frames_with_real_model
(with old 0.3 it panics: "default install would emit zero pose.frame
events").

Co-Authored-By: claude-flow <ruv@ruv.net>

v2/crates/cog-pose-estimation/src/main.rs

@@ -113,6 +113,18 @@ fn cmd_run(
     let cfg = CogConfig::load(&config_path)?;
     emit_event(&Event::run_started(COG_ID, &cfg));
 
+    // Disclosure: pose_v1 has no confidence head, so every frame carries the
+    // same `MODEL_TYPICAL_CONFIDENCE`. A `min_confidence` above that silently
+    // suppresses *all* pose.frame events. Warn loudly rather than drop quietly.
+    if cfg.min_confidence > cog_pose_estimation::inference::MODEL_TYPICAL_CONFIDENCE {
+        tracing::warn!(
+            min_confidence = cfg.min_confidence,
+            model_typical_confidence = cog_pose_estimation::inference::MODEL_TYPICAL_CONFIDENCE,
+            "configured min_confidence exceeds the model's typical confidence; \
+             no pose.frame events will be emitted until this is lowered"
+        );
+    }
+
     let engine = InferenceEngine::with_adapter(adapter.as_deref())?;
     if engine.is_calibrated() {
         tracing::info!("per-room calibration adapter loaded");