feat: add terrain-core, tma, and unitdat crates with parsing functionality

- Introduced `terrain-core` crate for loading and processing terrain mesh data.
- Added `tma` crate for parsing mission files, including footer and object records.
- Created `unitdat` crate for reading unit data files with validation of structure.
- Implemented error handling and tests for all new crates.
- Documented object registry format and rendering pipeline in specifications.

1 files changed, 1 insertions, 0 deletions

diff --git a/mkdocs.yml b/mkdocs.yml
index c7bf965..5630470 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -34,6 +34,7 @@ nav:
       - Texture (Texm): specs/texture.md
       - Materials index: specs/materials-texm.md
       - Missions: specs/missions.md
+      - Object registry (objects.rlb): specs/object-registry.md
       - MSH animation: specs/msh-animation.md
       - MSH core: specs/msh-core.md
       - Network system: specs/network.md