feat: add document reading, multi-doc summarization, and batch rename for Shira

Enable the AI assistant to read full documents from network storage (PDF/DOCX/TXT),
summarize multiple documents, and batch-rename files. Key changes:

- Raise text extraction limit from 2,000 to 100,000 chars (configurable)
- Add agentic loop in SmartAssistantService for multi-turn tool execution
- New tools: read_document, read_multiple_documents, batch_rename_documents
- New API endpoints: readDocument, readMultipleDocuments, batchRename
- New integration settings: maxDocumentChars, agenticLoopEnabled, maxAgenticLoops

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

manifest.json

@@ -3,11 +3,11 @@
     "module": "SmartAssistant",
     "description": "Unified AI Assistant for Legal CRM — floating chat with case memory, office alerts, and AI Gateway integration",
     "author": "klear",
-    "version": "2.5.5",
+    "version": "2.6.0",
     "acceptableVersions": [
         ">=8.0.0"
     ],
-    "releaseDate": "2026-04-06",
+    "releaseDate": "2026-04-09",
     "php": [
         ">=8.1"
     ]