Kick off (#1)

* Kick off
* Update LICENSE copyright

migrations/0001_initial.sql

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+CREATE TABLE check_results (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  monitor_name TEXT NOT NULL,
+  checked_at INTEGER NOT NULL,
+  status TEXT NOT NULL,
+  response_time_ms INTEGER,
+  error_message TEXT,
+  attempts INTEGER NOT NULL
+);
+
+CREATE INDEX idx_results_monitor_time ON check_results(monitor_name, checked_at DESC);
+
+CREATE TABLE monitor_state (
+  monitor_name TEXT PRIMARY KEY,
+  current_status TEXT NOT NULL,
+  consecutive_failures INTEGER DEFAULT 0,
+  last_status_change INTEGER,
+  last_checked INTEGER
+);
+
+CREATE TABLE alerts (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  monitor_name TEXT NOT NULL,
+  alert_type TEXT NOT NULL,
+  sent_at INTEGER NOT NULL,
+  alert_name TEXT NOT NULL,
+  success INTEGER NOT NULL
+);
+
+CREATE INDEX idx_alerts_monitor ON alerts(monitor_name, sent_at DESC);

migrations/0002_aggregation.sql

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+-- Hourly aggregated check results for data retention
+CREATE TABLE check_results_hourly (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  monitor_name TEXT NOT NULL,
+  hour_timestamp INTEGER NOT NULL,
+  total_checks INTEGER NOT NULL,
+  successful_checks INTEGER NOT NULL,
+  failed_checks INTEGER NOT NULL,
+  avg_response_time_ms INTEGER,
+  min_response_time_ms INTEGER,
+  max_response_time_ms INTEGER
+);
+
+CREATE UNIQUE INDEX idx_hourly_monitor_hour ON check_results_hourly(monitor_name, hour_timestamp);

migrations/0003_indexes.sql

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+-- Indexes for status page & aggregation performance
+CREATE INDEX idx_checked_at ON check_results(checked_at);
+CREATE INDEX idx_hourly_timestamp ON check_results_hourly(hour_timestamp);
+
+-- Optional covering index for aggregation queries
+-- Includes all columns needed for hourly aggregation to avoid table lookups
+CREATE INDEX idx_checked_at_monitor_covering ON check_results(checked_at, monitor_name, status, response_time_ms);