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/rag_service.py

@@ -168,3 +168,42 @@ async def search(
         }
         for row in rows
     ]
+
+
+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]:  # Cap at 5 for prompt size
+        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]],
+    exclude_tree_id: Optional[UUID] = None,
+) -> list[dict[str, Any]]:
+    """Extract unique suggested flows from RAG results."""
+    seen_tree_ids: set[str] = set()
+    suggestions = []
+
+    for r in rag_results:
+        tid = r["tree_id"]
+        if exclude_tree_id and tid == str(exclude_tree_id):
+            continue
+        if tid in seen_tree_ids:
+            continue
+        if r["similarity"] < 0.3:
+            continue
+        seen_tree_ids.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]