feat: camera_records table migration

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/migrations/004_camera_records.sql

@@ -0,0 +1,18 @@
+-- migrations/004_camera_records.sql
+-- Add camera_records table for TimerCamera-F door counter events
+-- Apply: sqlite3 <db_file> < migrations/004_camera_records.sql
+
+CREATE TABLE IF NOT EXISTS camera_records (
+    id           INTEGER PRIMARY KEY AUTOINCREMENT,
+    device_id    TEXT    NOT NULL,
+    location_id  TEXT    NOT NULL,
+    period_start INTEGER NOT NULL,
+    period_end   INTEGER NOT NULL,
+    entries      INTEGER NOT NULL,
+    exits        INTEGER NOT NULL,
+    created_at   DATETIME DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(device_id, period_start)
+);
+
+CREATE INDEX IF NOT EXISTS idx_camera_location_time
+    ON camera_records(location_id, period_start);