feat: add latent frequency

[ryanontheinside]

Add LatentFrequency Processor for Latent Domain Frequency Control

This PR introduces a new LatentFrequencyProcessor that enables frequency domain manipulation directly in latent space, providing more efficient control over image characteristics compared to pixel-space frequency filtering.

Key Features:

• Three-band frequency control: Independent multipliers for low (structure/composition), mid (textures/patterns), and high (fine details/edges) frequency components
• Configurable frequency boundaries: Adjustable cutoff points between frequency bands (0.1-0.9 range)
• Latent domain processing: Operates directly on latent representations [B, C, H/8, W/8] for computational efficiency
• Safety constraints: Parameter clamping and value limits to prevent extreme outputs
• Standalone processor: Inherits from BasePreprocessor (no pipeline state required)

Parameters:

• low_freq_multiplier, mid_freq_multiplier, high_freq_multiplier (0.0-3.0, default 1.0)
• low_mid_cutoff, mid_high_cutoff (0.1-0.9, defaults 0.3 and 0.7)

Use Cases:

• Detail enhancement/reduction
• Texture control and artistic stylization
• Composition refinement
• More efficient alternative to pixel-space frequency filtering

The processor integrates with the existing preprocessor framework and includes comprehensive parameter validation and safety measures.