dsh-media-guard: DeepSeek Harness Image Optimization and Smart Preservation Plugin

`dsh-media-guard` is a plugin specifically designed for the DeepSeek Harness (DSH) to address challenges in multimodal agent development, such as oversized image payloads, redundant accumulation, and unclear retention policies. Operating within the `llm/stream` pipeline, it optimizes image views through intelligent compression (WebP), content deduplication, and priority-based retention strategies. The plugin supports three operating modes: `protect` (compression and overflow handling, default), `observe` (inventory reporting only), and `optimize` (compression without payload leakage). It provides detailed budget configurations (e.g., byte limits) and route-specific override options, ensuring that image processing complies with adapter limits without altering the original logs.