fix: Sort pipeline tasks by dependency order instead of priority+createdAt

The Execution tab's PipelinePhaseGroup was using sortByPriorityAndQueueTime
which ignores task dependencies entirely. Tasks now sort topologically via
topologicalSortPhases, matching the Plan tab's TaskGraph behavior.

- Add listInitiativeTaskDependencies tRPC procedure (bulk fetch)
- Fetch task deps in PipelineTab, group by phase, pass through
- Replace priority sort with topological sort in PipelinePhaseGroup
- Show "blocked by N" count on PipelineTaskCard

apps/server/trpc/routers/task.ts

@@ -183,6 +183,19 @@ export function taskProcedures(publicProcedure: ProcedureBuilder) {
         return edges;
       }),
 
+    listInitiativeTaskDependencies: publicProcedure
+      .input(z.object({ initiativeId: z.string().min(1) }))
+      .query(async ({ ctx, input }) => {
+        const taskRepo = requireTaskRepository(ctx);
+        const tasks = await taskRepo.findByInitiativeId(input.initiativeId);
+        const edges: Array<{ taskId: string; dependsOn: string[] }> = [];
+        for (const t of tasks) {
+          const deps = await taskRepo.getDependencies(t.id);
+          if (deps.length > 0) edges.push({ taskId: t.id, dependsOn: deps });
+        }
+        return edges;
+      }),
+
     approveTask: publicProcedure
       .input(z.object({ taskId: z.string().min(1) }))
       .mutation(async ({ ctx, input }) => {