Add initial schema for entries and settings tables

- Created 'entries' table to track time entries with fields for date, start time, end time, pause minutes, location, and entry type.
- Created 'settings' table to store key-value pairs for application settings with an updated timestamp.

schema.sql

@@ -0,0 +1,15 @@
+CREATE TABLE IF NOT EXISTS entries (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  date TEXT NOT NULL UNIQUE,
+  start_time TEXT,
+  end_time TEXT,
+  pause_minutes INTEGER NOT NULL DEFAULT 0,
+  location TEXT DEFAULT 'office' CHECK(location IN ('office', 'home')),
+  entry_type TEXT DEFAULT 'work' CHECK(entry_type IN ('work', 'vacation', 'flextime'))
+);
+
+CREATE TABLE IF NOT EXISTS settings (
+  key TEXT PRIMARY KEY,
+  value TEXT NOT NULL,
+  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);