dsh-plugin-observatory: DSH Plugin Pre-installation Audit and Bounded Loader Observation

`dsh-plugin-observatory` is a read-only audit plugin for DSH maintained by CMSKL, designed to provide static compatibility checks before installation and bounded lifecycle observation after activation for plugin authors and maintainers. The plugin consists of two core tools: `plugin_audit` is used to audit the `package.json` and `dsh.bundle.patch` of local plugin packages, checking version ranges, dependency declarations, patch structures, and unevaluated expressions, and outputting deterministic machine-readable reports indicating `compatible`, `needs-review`, or `incompatible`; `plugin_observe` projects current non-group Loader entries, displaying the activated bounded read-only state.