feat: reconcile SQLite tables and columns at startup

internal/database/schemas/knowledge.sql

@@ -0,0 +1,44 @@
+-- Latest SQLite structure. Update these definitions when adding tables or columns.
+
+CREATE TABLE knowledge_base_items (
+    id TEXT PRIMARY KEY,
+    category TEXT NOT NULL,
+    title TEXT NOT NULL,
+    file_path TEXT NOT NULL,
+    content TEXT,
+    created_at DATETIME NOT NULL,
+    updated_at DATETIME NOT NULL
+);
+
+CREATE TABLE knowledge_embeddings (
+    id TEXT PRIMARY KEY,
+    item_id TEXT NOT NULL,
+    chunk_index INTEGER NOT NULL,
+    chunk_text TEXT NOT NULL,
+    embedding TEXT NOT NULL,
+    sub_indexes TEXT NOT NULL DEFAULT '',
+    embedding_model TEXT NOT NULL DEFAULT '',
+    embedding_dim INTEGER NOT NULL DEFAULT 0,
+    created_at DATETIME NOT NULL,
+    FOREIGN KEY (item_id) REFERENCES knowledge_base_items(id) ON DELETE CASCADE
+);
+
+CREATE TABLE knowledge_retrieval_logs (
+    id TEXT PRIMARY KEY,
+    conversation_id TEXT,
+    message_id TEXT,
+    query TEXT NOT NULL,
+    risk_type TEXT,
+    retrieved_items TEXT,
+    created_at DATETIME NOT NULL
+);
+
+CREATE INDEX idx_knowledge_embeddings_item_id ON knowledge_embeddings(item_id);
+
+CREATE INDEX idx_knowledge_items_category ON knowledge_base_items(category);
+
+CREATE INDEX idx_knowledge_retrieval_logs_conversation ON knowledge_retrieval_logs(conversation_id);
+
+CREATE INDEX idx_knowledge_retrieval_logs_created_at ON knowledge_retrieval_logs(created_at);
+
+CREATE INDEX idx_knowledge_retrieval_logs_message ON knowledge_retrieval_logs(message_id);