feat(agent): Gradio-powered LangGraph agent chat with streaming, tool calls, file upload, conversation persistence

- Gradio 5.50.0 ChatInterface with type='messages' streaming
- LangGraph create_react_agent with InMemorySaver checkpointer
- 4 @tool functions: search_dashboards, get_health_summary, list_environments, get_task_status
- Structured ChatMessage metadata (7 discriminator types: stream_token, tool_start/end/error, confirm_required, confirm_resolved, error)
- HITL resume via second submit() with interrupt_before/Command
- Dual-identity RBAC: service JWT + user JWT for tool calls
- File upload (10 MB limit, pdfplumber/xlsx/JSON parser)
- Conversation persistence via POST /api/agent/conversations/save
- REST API: list, history, archive conversations; multi-tab gate; LLM config
- LLM provider selection via Admin -> LLM Settings (assistant_planner_provider)
- Svelte 5 AgentChatModel with stream event queue, dedup, stream_status watcher
- MarkdownRenderer using svelte-markdown with semantic Tailwind tokens
- ToolCallCard (3 states: executing/completed/failed)
- ConversationList with search, date grouping, infinite scroll
- ConnectionIndicator with Gradio health status
- /agent route with two-column layout
- Vite proxy /api/agent/gradio -> Gradio SSE
- Fixed: not_() SQLAlchemy operator, route collision with _admin_routes
- Fixed: conversation_id -> id normalization, .pyc cache staleness
- Fixed: event.data array parsing (Gradio returns [jsonStr, null])
- Requirements pinned: gradio==5.50.0, pydantic>=2.7,<=2.12.3

backend/src/app.py

@@ -15,6 +15,7 @@ import asyncio
 from contextlib import asynccontextmanager
 import os
 from pathlib import Path
+import sys
 
 # project_root is used for static files mounting
 project_root = Path(__file__).resolve().parent.parent.parent
@@ -31,6 +32,7 @@ from .api import auth
 from .api.routes import (
     admin,
     admin_api_keys,
+    agent_conversations,
     assistant,
     clean_release,
     clean_release_v2,
@@ -396,6 +398,8 @@ app.include_router(dashboards.router)
 app.include_router(datasets.router)
 app.include_router(reports.router)
 app.include_router(assistant.router, prefix="/api/assistant", tags=["Assistant"])
+app.include_router(agent_conversations.agent_router, tags=["Agent"])
+app.include_router(agent_conversations.router, tags=["Assistant"])
 app.include_router(clean_release.router)
 app.include_router(clean_release_v2.router)
 app.include_router(profile.router)