feat: add account management, email verification, AI fixes, and user guides

- Profile settings, account transfer, delete/leave account flows
- Email verification with JWT tokens and Resend integration
- AI assistant/copilot fixes: markdown rendering, shared RAG helpers,
  token tracking, input refocus, model_validate usage
- User guides hub + detail pages with 13 topic guides
- Sidebar and top bar navigation for guides

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

backend/app/services/assistant_chat_service.py

@@ -12,7 +12,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.ai_provider import get_ai_provider
 from app.models.assistant_chat import AssistantChat
-from app.services import rag_service
+from app.services.rag_service import search as rag_search, build_rag_context, extract_suggested_flows
 
 logger = logging.getLogger(__name__)
 
@@ -33,36 +33,6 @@ When answering:
 """
 
 
-def _build_rag_context(rag_results: list[dict[str, Any]]) -> str:
-    """Format RAG results into a system prompt section."""
-    if not rag_results:
-        return ""
-
-    parts = ["\n--- RELEVANT FLOWS FROM TEAM LIBRARY ---"]
-    for r in rag_results[:5]:
-        parts.append(f"- [{r['tree_type']}] {r['tree_name']}: {r['chunk_text'][:200]}")
-
-    return "\n".join(parts)
-
-
-def _extract_suggested_flows(rag_results: list[dict[str, Any]]) -> list[dict[str, Any]]:
-    """Extract unique suggested flows from RAG results."""
-    seen: set[str] = set()
-    suggestions = []
-    for r in rag_results:
-        tid = r["tree_id"]
-        if tid in seen or r["similarity"] < 0.3:
-            continue
-        seen.add(tid)
-        suggestions.append({
-            "tree_id": tid,
-            "tree_name": r["tree_name"],
-            "tree_type": r["tree_type"],
-            "relevance_snippet": r["chunk_text"][:150],
-        })
-    return suggestions[:3]
-
-
 def _auto_title(message: str) -> str:
     """Generate a short title from the first user message."""
     title = message.strip()[:100]
@@ -113,7 +83,7 @@ async def send_message(
         chat.title = _auto_title(message)
 
     # RAG search
-    rag_results = await rag_service.search(
+    rag_results = await rag_search(
         query=message,
         account_id=account_id,
         db=db,
@@ -121,7 +91,7 @@ async def send_message(
     )
 
     # Build system prompt
-    system_prompt = ASSISTANT_SYSTEM_PROMPT + _build_rag_context(rag_results)
+    system_prompt = ASSISTANT_SYSTEM_PROMPT + build_rag_context(rag_results)
 
     # Build messages for AI
     ai_messages = []
@@ -147,6 +117,6 @@ async def send_message(
     chat.total_input_tokens += input_tokens
     chat.total_output_tokens += output_tokens
 
-    suggested_flows = _extract_suggested_flows(rag_results)
+    suggested_flows = extract_suggested_flows(rag_results)
 
     return ai_content, suggested_flows, chat