Implement Signal Generation Functions for Gravitational Wave Waveforms

Overview

We need low-level signal generation functions to produce gravitational wave strain data. These should be pure functions that take physical parameters as input and return strain time series, without needing to inherit from our simulator classes.

Function Specifications

• Pure functions only - no class inheritance required
• Standard numpy arrays for strain output
• GPS time handling: Support for realistic GPS timestamps
• Phase continuity: Signals must be continuous across segment boundaries