Phase 4c: bulk document upload with live SSE progress

New UploadSheet on the case detail page wraps react-dropzone + a
selector for doc_type. Files post to
POST /api/cases/{n}/documents/upload-tagged as multipart form-data;
the returned task_id is streamed via GET /api/progress/{task_id}
through the new lib/sse.ts EventSource wrapper.

Each upload row shows a per-file progress bar that transitions to
success/error on the terminal SSE payload. Closing the stream inside
the message handler avoids EventSource's auto-reconnect after EOF.

Phase 4 (task 86) is now complete end-to-end: create, upload, edit.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web-ui/src/app/cases/[caseNumber]/page.tsx

@@ -11,6 +11,7 @@ import { CaseHeader } from "@/components/cases/case-header";
 import { CaseEditDialog } from "@/components/cases/case-edit-dialog";
 import { WorkflowTimeline } from "@/components/cases/workflow-timeline";
 import { DocumentsPanel } from "@/components/cases/documents-panel";
+import { UploadSheet } from "@/components/documents/upload-sheet";
 import { useCase } from "@/lib/api/cases";
 
 /*
@@ -56,18 +57,21 @@ export default function CaseDetailPage({
               <Card className="bg-surface border-rule shadow-sm">
                 <CardContent className="px-6 py-5">
                   <Tabs defaultValue="overview" dir="rtl">
-                    <TabsList className="bg-rule-soft/60">
-                      <TabsTrigger value="overview">סקירה</TabsTrigger>
-                      <TabsTrigger value="documents">
-                        מסמכים
-                        {data?.documents && (
-                          <span className="ms-1.5 text-[0.7rem] text-ink-muted tabular-nums">
-                            ({data.documents.length})
-                          </span>
-                        )}
-                      </TabsTrigger>
-                      <TabsTrigger value="actions">פעולות</TabsTrigger>
-                    </TabsList>
+                    <div className="flex items-center justify-between gap-3 mb-1">
+                      <TabsList className="bg-rule-soft/60">
+                        <TabsTrigger value="overview">סקירה</TabsTrigger>
+                        <TabsTrigger value="documents">
+                          מסמכים
+                          {data?.documents && (
+                            <span className="ms-1.5 text-[0.7rem] text-ink-muted tabular-nums">
+                              ({data.documents.length})
+                            </span>
+                          )}
+                        </TabsTrigger>
+                        <TabsTrigger value="actions">פעולות</TabsTrigger>
+                      </TabsList>
+                      <UploadSheet caseNumber={caseNumber} />
+                    </div>
 
                     <TabsContent value="overview" className="mt-5 space-y-4">
                       <div>