feat(dimentorin): AI agent RAG (embedding materi -> Qdrant + chat via 9router)

- ENV: AI_LLM_BASE_URL/API_KEY/MODEL, AI_EMBEDDING_MODEL (gemini-embedding-001), QDRANT_URL
- ai_agent module: chunking materi, embed_text + chat_completion (9router, SSE parse), Qdrant repo (dimentorin_materi collection, 3072d cosine)
- routes: POST /ai/chat (RAG answer + sources), POST /ai/materials/{id}/index, POST /ai/reindex
- e2e verified: reindex 3 chunks; chat 'ownership' -> materi Rust paling relevan 0.88; chat 'endpoint axum' -> materi Axum 0.82; jawaban gronding konteks

imphnen-dimentorin/src/ai_agent/infrastructure/http/routes.rs

@@ -0,0 +1,18 @@
+use super::handlers::{post_chat, post_index_material, post_reindex_all};
+use crate::ai_agent::application::RagServiceImpl;
+use crate::ai_agent::domain::RagService;
+use crate::ai_agent::infrastructure::QdrantRagRepository;
+use axum::{Extension, Router, routing::post};
+use imphnen_libs::AppState;
+use sea_orm::DatabaseConnection;
+use std::sync::Arc;
+
+pub fn ai_agent_routes(db: DatabaseConnection, _state: Arc<AppState>) -> Router {
+	let repo = Arc::new(QdrantRagRepository::new());
+	let service: Arc<dyn RagService> = Arc::new(RagServiceImpl::new(repo, db));
+	Router::new()
+		.route("/ai/chat", post(post_chat))
+		.route("/ai/materials/{id}/index", post(post_index_material))
+		.route("/ai/reindex", post(post_reindex_all))
+		.layer(Extension(service))
+}