Make bulk upload documents clickable with storage verification

- Add bucket/objectKey to file select in listProjectsByRoundRequirements
- Add verifyFilesExist endpoint to bulk-check file existence in MinIO
- Make uploaded filenames clickable links that open presigned download URLs
- Verify files exist in storage on page load, show re-upload button if missing

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

src/server/routers/file.ts

@@ -1295,6 +1295,8 @@ export const fileRouter = router({
               size: true,
               createdAt: true,
               requirementId: true,
+              bucket: true,
+              objectKey: true,
             },
           },
         },
@@ -1487,4 +1489,37 @@ export const fileRouter = router({
 
       return { uploadUrl, file }
     }),
+
+  /**
+   * Verify that files actually exist in storage (MinIO/S3).
+   * Returns a map of objectKey → exists boolean.
+   */
+  verifyFilesExist: adminProcedure
+    .input(
+      z.object({
+        files: z.array(
+          z.object({
+            bucket: z.string(),
+            objectKey: z.string(),
+          })
+        ).max(200),
+      })
+    )
+    .query(async ({ input }) => {
+      const { getMinioClient } = await import('@/lib/minio')
+      const client = getMinioClient()
+
+      const results: Record<string, boolean> = {}
+      await Promise.all(
+        input.files.map(async ({ bucket, objectKey }) => {
+          try {
+            await client.statObject(bucket, objectKey)
+            results[objectKey] = true
+          } catch {
+            results[objectKey] = false
+          }
+        })
+      )
+      return results
+    }),
 })