fix: Fix review task completion bug + add initiative-level Request Changes

Critical: review/merge tasks hit an early return in handleTaskCompleted()
that skipped the phase completion check, leaving phases stuck in
in_progress forever. Changed to an if-block wrapping only the merge step.

Also adds requestChangesOnInitiative() which creates/reuses a
"Finalization" phase for initiative-level review feedback, with dedup
guards for both phase and initiative request-changes flows.

apps/server/trpc/routers/initiative.ts

@@ -335,5 +335,19 @@ export function initiativeProcedures(publicProcedure: ProcedureBuilder) {
         await orchestrator.approveInitiative(input.initiativeId, input.strategy);
         return { success: true };
       }),
+
+    requestInitiativeChanges: publicProcedure
+      .input(z.object({
+        initiativeId: z.string().min(1),
+        summary: z.string().trim().min(1),
+      }))
+      .mutation(async ({ ctx, input }) => {
+        const orchestrator = requireExecutionOrchestrator(ctx);
+        const result = await orchestrator.requestChangesOnInitiative(
+          input.initiativeId,
+          input.summary,
+        );
+        return { success: true, taskId: result.taskId };
+      }),
   };
 }