feat: restrain document naming to a subject-only prompt contract

Shira now supplies a subject, never a filename or numbering. The TEMPLATE / FREE-DOC
/ FOLDER guidance in prompt_builder instructs the model to pass title / documentSubject
as a short Hebrew subject (no date, case number, contact, extension or path separators),
and to keep the final filename of write_document_to_folder clean. Server-side enforcement
lives in SmartAssistant CaseFolderManager (rule N1).

Refs Task Master #10

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

.taskmaster/tasks/tasks.json

@@ -116,12 +116,24 @@
         "priority": "high",
         "subtasks": [],
         "updatedAt": "2026-05-26T13:50:11.559Z"
+      },
+      {
+        "id": "10",
+        "title": "feat: restrain LLM file naming to subject-only (prompt guidance)",
+        "description": "Shira supplies a subject only; the system names files and resolves duplicates.",
+        "details": "prompt_builder.py: TEMPLATE/FREE-DOC/FOLDER bullets instruct title/documentSubject as short Hebrew subject (no date/case#/contact/extension/slashes); write_document_to_folder final filename clean; create_subfolder/rename_item plain names. Server-side enforcement lives in SmartAssistant CaseFolderManager.",
+        "testStrategy": "",
+        "status": "in-progress",
+        "dependencies": [],
+        "priority": "medium",
+        "subtasks": [],
+        "updatedAt": "2026-06-03T07:31:11.691Z"
       }
     ],
     "metadata": {
       "version": "1.0.0",
-      "lastModified": "2026-05-26T13:50:11.559Z",
-      "taskCount": 9,
+      "lastModified": "2026-06-03T07:31:11.692Z",
+      "taskCount": 10,
       "completedCount": 6,
       "tags": [
         "master"