feat(tui): render self-improvement review summaries in the transcript

The Ink TUI (\`hermes --tui\` + dashboard \`/chat\`) had no wiring for the
background self-improvement review. When the review fired and patched
a skill or saved a memory entry, the change landed but the user had
no visual indication it happened — only the CLI had a print surface
for the '💾 Self-improvement review: …' line.

Changes:

- tui_gateway/server.py: in _init_session, attach
  agent.background_review_callback to an _emit('review.summary',
  sid, {text}) closure. Wrapped in try/except so agents with locked
  attribute slots don't break session startup.
- ui-tui/src/app/createGatewayEventHandler.ts: handle 'review.summary'
  by routing ev.payload.text through sys(…), matching the existing
  'background.complete' pattern. Empty / whitespace payloads are
  ignored so the transcript never gets a blank system line.
- ui-tui/src/gatewayTypes.ts: extend the GatewayEvent discriminated
  union with { type: 'review.summary', payload?: { text?: string } }.

Gateway platforms (Telegram, Discord, Slack, …) already route the
review summary via background_review_callback → post-delivery queue
in gateway/run.py, so they pick up the new 'Self-improvement review:'
prefix from the companion run_agent change with no platform edits.

Tests:
- tests/tui_gateway/test_review_summary_callback.py (Python, 2 tests):
  _init_session attaches a callback that emits the right event; the
  callback path survives agents that can't accept the attribute.
- ui-tui/src/__tests__/createGatewayEventHandler.test.ts (vitest, 2
  new cases): review.summary events feed sys(...) with the full text;
  empty / missing payloads are no-ops.
- TypeScript type-check passes.
- tui_gateway suite: 64/64 pass.

ui-tui/src/app/createGatewayEventHandler.ts

@@ -510,6 +510,20 @@ export function createGatewayEventHandler(ctx: GatewayEventHandlerContext): (ev:
 
         return
 
+      case 'review.summary': {
+        // Self-improvement background review emitted a persistent summary
+        // of what it saved to memory/skills. Surface it as a system line
+        // in the transcript so it never gets lost to a transient status
+        // flash. Python-side already formats it as "💾 Self-improvement
+        // review: …".
+        const text = String(ev.payload?.text ?? '').trim()
+        if (text) {
+          sys(text)
+        }
+
+        return
+      }
+
       case 'subagent.spawn_requested':
         // Child built but not yet running (waiting on ThreadPoolExecutor slot).
         // Preserve completed state if a later event races in before this one.