feat(chat): live turn metrics — telemetry reducer + rendering

Consume wire/transport-contract 0.3.0 (step-complete event + timing
fields on usage/tool-result/done). Pure core/telemetry module:
foldMetricEvent (reducer) + derived selectors (stepTps, turnTps, etc).
TelemetryState is pure data, no active-turn tracking — consumers pass
turnId to selectors. ChatStore wires foldMetricEvent into handleDelta
and exposes telemetry + currentTurnId. ChatView shows step-metrics
footer (time/TPS/tokens) on assistant text bubbles and durationMs badge
on tool cards. New TurnSummary component renders turn-level stats
(wall-clock, tokens, steps, TPS) in a DaisyUI stats block. Extended
live-probe to verify telemetry events against bin/up (pending backend
restart). 336 tests, typecheck 0, biome clean, build ok.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/core/telemetry/index.ts b/src/core/telemetry/index.ts
new file mode 100644
index 0000000..a528b0d
--- /dev/null
+++ b/src/core/telemetry/index.ts
@@ -0,0 +1,14 @@
+export { foldMetricEvent, initialState } from "./reducer";
+export {
+	stepCount,
+	stepMetrics,
+	stepToolDuration,
+	stepTps,
+	totalDecodeMs,
+	totalInputTokens,
+	totalOutputTokens,
+	turnMetrics,
+	turnTps,
+	turnTtft,
+} from "./selectors";
+export type { StepMetrics, TelemetryState, TurnMetrics } from "./types";