feat: implement document management functionality for search
* developed search engine capabilities for documents using TF-IDF indexing * utility functions for tokenization and frequency counting for document content
···1+CREATE TABLE IF NOT EXISTS documents (
2+ id INTEGER PRIMARY KEY AUTOINCREMENT,
3+ title TEXT NOT NULL,
4+ body TEXT NOT NULL,
5+ created_at DATETIME NOT NULL,
6+ doc_kind INTEGER NOT NULL
7+);
8+9+CREATE INDEX IF NOT EXISTS idx_documents_doc_kind ON documents(doc_kind);
10+CREATE INDEX IF NOT EXISTS idx_documents_created_at ON documents(created_at);