feat(memory): implement OpenRouter + pgvector memory pipeline

.scripts/memory/schema.sql

@@ -0,0 +1,20 @@
+CREATE EXTENSION IF NOT EXISTS vector;
+
+CREATE TABLE IF NOT EXISTS memory_primary (
+  id TEXT PRIMARY KEY,
+  source TEXT NOT NULL,
+  content TEXT NOT NULL,
+  content_hash TEXT NOT NULL,
+  embedding VECTOR(1536) NOT NULL,
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE TABLE IF NOT EXISTS memory_secure_audit (
+  id TEXT PRIMARY KEY,
+  source TEXT NOT NULL,
+  risk TEXT NOT NULL,
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE INDEX IF NOT EXISTS memory_primary_embedding_idx
+ON memory_primary USING ivfflat (embedding vector_cosine_ops) WITH (lists = 100);