build backend to collect and search using embeddings

backend/migrations/2025-01-03-init.sql

@@ -0,0 +1,11 @@
+CREATE TABLE IF NOT EXISTS cache (
+                                     id INTEGER PRIMARY KEY,
+                                     url TEXT NOT NULL UNIQUE,
+                                     response TEXT NOT NULL,
+                                     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+                                     ttl INTEGER DEFAULT 0
+);
+
+CREATE INDEX idx_url ON cache (url);
+CREATE INDEX idx_created_at ON cache (created_at);
+