Constexpr Sine Lookup Table

Generate a quarter-wave sine table at compile time for a DDS waveform generator, so no runtime trig and no float math is needed on the target.

Constraints

• 256 entries covering 0 to pi/2, stored as int16_t Q15.
• Table must be constexpr - computed by the compiler.
• Use a Taylor series; std::sin is not constexpr.
• Accuracy within 32 LSB of the true value.
• static_assert the endpoints.