refactor(#2077): collapse dev-assets tree in assets.rs to a nix/assets.nix pointer

hive-sh4re/src/assets.rs

@@ -12,17 +12,8 @@
 //! HIVE_ASSETS_DIR=$(pwd)/dev-assets cargo run ...
 //! ```
 //!
-//! where `dev-assets/` is laid out the same as the nix output:
-//!
-//! ```text
-//! dev-assets/
-//!   branding/
-//!     hyperhive.{svg,png}
-//!     agent-configs.{svg,png}
-//!   prompts/
-//!     system.md
-//!     claude-settings.json
-//! ```
+//! where `dev-assets/` mirrors the nix output's `branding/` + `prompts/`
+//! layout (canonical tree in `nix/assets.nix`).
 //!
 //! Each crate that wants a specific asset goes through one of the
 //! typed helpers (`branding_svg()`, `prompt_template()`, …) so the