dsh-memory-pyramid: Adding timeline memory to DeepSeek Harness

dsh-memory-pyramid is an MIT-licensed memory plugin for DeepSeek Harness (dsh). Its core mechanism adopts a dual-layer architecture: the bottom layer consists of an append-only, fixed-width (≤280 bytes) fact log, while the upper layer features a summary pyramid maintained autonomously by the Agent. Through a fixed reading budget mechanism, the number of rows read at startup remains constant regardless of the growth in total memory volume, effectively reducing recall costs. Plugin data is stored by default in the `dsh_memory` directory of the current working directory. Its plain text format supports Git management and Diff review, and it supports multi-process lock-free concurrent writing. It runs as a native DSH plugin with zero npm dependencies, no build steps required, and compatibility with Windows, Linux, macOS, and ARM64 architectures. Functionally, the plugin provides...