feat: add live progress during orchestrator plan generation

New SSE event orchestrator:planProgress streams phase/detail updates
from the planner to the frontend in real-time. The panel now shows
a scrollable log of planning steps instead of just "Generating plan..."

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/web/routes/orchestrator-routes.ts

@@ -45,6 +45,9 @@ export function registerOrchestratorRoutes(app: FastifyInstance, ctx: Orchestrat
     loop.on('stateChanged', (state, prevState) => {
       ctx.broadcast(SseEvent.OrchestratorStateChanged, { state, prevState });
     });
+    loop.on('planProgress', (phase, detail) => {
+      ctx.broadcast(SseEvent.OrchestratorPlanProgress, { phase, detail });
+    });
     loop.on('planReady', (plan) => {
       ctx.broadcast(SseEvent.OrchestratorPlanReady, { plan });
     });