Scheduler core with period keys and catch-up (Feature 20) (#171)

Co-authored-by: orchestrator-agent <20+orchestrator-agent@code.cubecraftcreations.com>

internal/db/schedule_runs.sql.go

@@ -0,0 +1,38 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.31.1
+// source: schedule_runs.sql
+
+package db
+
+import (
+	"context"
+)
+
+const claimScheduleRun = `-- name: ClaimScheduleRun :execrows
+INSERT INTO schedule_runs (id, schedule, period_key, created_at)
+VALUES (?, ?, ?, ?)
+ON CONFLICT (schedule, period_key) DO NOTHING
+`
+
+type ClaimScheduleRunParams struct {
+	ID        string
+	Schedule  string
+	PeriodKey string
+	CreatedAt string
+}
+
+// Claims one period of a schedule. The insert is the claim: 1 row means
+// this caller owns the period, 0 rows means it was already claimed.
+func (q *Queries) ClaimScheduleRun(ctx context.Context, arg ClaimScheduleRunParams) (int64, error) {
+	result, err := q.db.ExecContext(ctx, claimScheduleRun,
+		arg.ID,
+		arg.Schedule,
+		arg.PeriodKey,
+		arg.CreatedAt,
+	)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}